Building on Blockchain: A Developer’s Toolkit

Introduction to Blockchain Development

Blockchain technology has emerged as a groundbreaking innovation that has the potential to revolutionize various industries, from finance and healthcare to supply chain management and beyond. As the adoption of blockchain continues to grow, the demand for skilled blockchain developers is also on the rise. According to a report by Gartner, blockchain deployments across financial services ecosystems are at least three years away, indicating a significant opportunity for developers to enter this field.

For beginners, blockchain development can seem daunting, as it involves a unique set of tools, programming languages, and concepts. However, with the right resources and guidance, anyone can start their journey towards becoming a proficient blockchain developer. The significance of blockchain development for beginners lies in the following aspects:

1. Career Opportunities: The blockchain industry is expected to grow from $3 billion in 2020 to $39.7 billion by 2025, creating numerous job opportunities for developers with blockchain expertise.
2. Innovation: Blockchain technology enables the creation of decentralized applications (dApps) and smart contracts, which can solve real-world problems and transform traditional business models.
3. Future-proofing: As blockchain adoption increases, developers with blockchain skills will be well-positioned to adapt to the changing technological landscape and stay relevant in their careers.

The objective of this article is to provide a comprehensive guide to blockchain development tools and resources for beginners. We will explore the essential tools, including programming languages, integrated development environments (IDEs), frameworks, and libraries, that are commonly used in blockchain development. Additionally, we will highlight valuable resources such as online courses, tutorials, learning platforms, communities, books, and hands-on projects that can help beginners acquire the necessary skills and knowledge to succeed in this field.

By the end of this article, beginners will have a clear understanding of the blockchain development ecosystem and be equipped with the tools and resources needed to start building their own blockchain applications. Whether you are a student, a professional looking to transition into blockchain development, or simply curious about this technology, this guide will provide you with a solid foundation to begin your journey.

Essential Blockchain Development Tools

To begin your journey as a blockchain developer, it is crucial to familiarize yourself with the essential tools that will help you build, test, and deploy blockchain applications. In this section, we will explore the key programming languages, integrated development environments (IDEs), frameworks, libraries, and testing and deployment tools that are widely used in the blockchain development ecosystem.

1. Programming Languages for Blockchain

When it comes to blockchain development, several programming languages have gained popularity due to their unique features and compatibility with blockchain platforms. Here are some of the most commonly used languages:

• Solidity: Solidity is the primary language for developing smart contracts on the Ethereum blockchain. It is a contract-oriented, high-level language that is designed to target the Ethereum Virtual Machine (EVM). According to Etherscan, as of April 2023, there are over 1.5 million verified smart contracts on the Ethereum network, with the majority written in Solidity.
• Rust: Rust is a systems programming language that focuses on safety, speed, and memory efficiency. It has gained traction in the blockchain space due to its ability to prevent common programming errors and its suitability for building high-performance blockchain infrastructure. Projects like Solana and Polkadot have adopted Rust as their primary language.
• Go (Golang): Go is a statically-typed language developed by Google that is known for its simplicity, concurrency support, and efficient memory management. It has become a popular choice for building blockchain clients, such as Geth (Go Ethereum) and Hyperledger Fabric.

Other languages like Java, Python, C++, and JavaScript are also used in blockchain development, depending on the specific platform and requirements.

2. Integrated Development Environments (IDEs)

IDEs are software applications that provide a comprehensive environment for writing, testing, and debugging code. Some of the most popular IDEs for blockchain development include:

• Remix IDE: Remix is a browser-based IDE specifically designed for Solidity development. It offers a user-friendly interface for writing, compiling, and testing smart contracts, making it an excellent choice for beginners. Remix also provides a built-in debugger and a simulated Ethereum environment for testing contracts.
• Truffle Suite: Truffle is a development framework for Ethereum that simplifies the process of building, testing, and deploying smart contracts. It includes features like automated contract testing, scriptable deployment, and a interactive console for interacting with contracts. Truffle integrates well with other tools like Ganache and Drizzle.
• Hardhat: Hardhat is a flexible development environment for Ethereum that focuses on developer experience and extensibility. It provides a rich set of features, including fast contract compilation, advanced debugging capabilities, and support for multiple networks. Hardhat also integrates with popular tools like Ethers.js and Waffle.
• Visual Studio Code: Visual Studio Code is a lightweight and extensible code editor that supports a wide range of programming languages. It has gained popularity among blockchain developers due to its rich ecosystem of extensions, including those specifically designed for Solidity and other blockchain-related languages.

3. Blockchain Development Frameworks and Libraries

Blockchain development frameworks and libraries provide a set of tools and abstractions that simplify the process of building blockchain applications. Some of the most widely used frameworks and libraries include:

• Ethereum Development Tools:
• Web3.js: A JavaScript library that allows developers to interact with Ethereum nodes using HTTP, IPC, or WebSocket protocols. It provides a convenient way to send transactions, deploy contracts, and read blockchain data from client-side applications.
• Ethers.js: A complete Ethereum library and wallet implementation in JavaScript, designed to be compact, flexible, and easy to use. It supports both browser and Node.js environments.
• Truffle: As mentioned earlier, Truffle is a popular development framework for Ethereum that provides a suite of tools for contract compilation, testing, and deployment.
• Hardhat: Hardhat is another powerful development environment for Ethereum that offers advanced features and extensibility.
• Hyperledger Fabric: Hyperledger Fabric is an open-source, permissioned blockchain framework designed for enterprise use cases. It provides a modular architecture that allows developers to build and deploy distributed ledger solutions with a high degree of confidentiality, scalability, and flexibility.
• Corda: Corda is an open-source blockchain platform that focuses on privacy and security for building decentralized applications in the financial industry. It offers a unique architecture that enables the development of interoperable and scalable applications while ensuring data privacy and compliance with regulations.
• IPFS (InterPlanetary File System): IPFS is a decentralized file storage system that allows users to store and share files in a distributed manner. It is often used in conjunction with blockchain applications to store large amounts of data off-chain while maintaining the integrity and immutability of the data.

4. Blockchain Testing and Deployment Tools

Testing and deployment are critical aspects of blockchain development that ensure the correctness and reliability of smart contracts and applications. Some essential tools for testing and deployment include:

• Ganache: Ganache is a personal Ethereum blockchain that allows developers to create a local development environment for testing smart contracts. It provides a graphical user interface and a command-line interface for easy interaction with the simulated blockchain.
• Remix IDE: In addition to its development features, Remix IDE also provides built-in testing and deployment capabilities. It allows developers to test smart contracts using various testing frameworks and deploy contracts to different Ethereum networks.
• Truffle Suite: Truffle offers a comprehensive testing framework that enables developers to write and run automated tests for smart contracts. It also provides a migration system for managing contract deployments and upgrades.
• Infura: Infura is a widely-used Ethereum API and node infrastructure provider that allows developers to easily connect their applications to the Ethereum network without running their own nodes. It offers a reliable and scalable infrastructure for deploying and interacting with smart contracts.

By leveraging these essential blockchain development tools, beginners can streamline their development process, write more efficient and secure code, and deploy their applications with confidence. As you progress in your blockchain development journey, it is important to continuously explore and experiment with new tools and frameworks to stay up-to-date with the rapidly evolving blockchain ecosystem.

Blockchain Development Resources for Beginners

As a beginner in blockchain development, having access to the right resources can make a significant difference in your learning journey. In this section, we will explore various online courses, tutorials, learning platforms, communities, books, and hands-on projects that can help you acquire the knowledge and skills necessary to become a proficient blockchain developer.

1. Online Courses and Tutorials

Online courses and tutorials are excellent starting points for learning blockchain development. They provide structured content, practical examples, and hands-on exercises to help you grasp the concepts and apply them in real-world scenarios. Some popular platforms and courses include:

• Coursera: Coursera offers a range of blockchain courses from top universities and institutions, such as the Blockchain Specialization by the University at Buffalo and The State University of New York, and the Blockchain Basics course by the University of California, Irvine.
• Udemy: Udemy is a popular online learning platform that hosts numerous blockchain development courses. Some highly-rated courses include the Ethereum Blockchain Developer Bootcamp With Solidity and the Blockchain A-Z™: Learn How To Build Your First Blockchain.
• FreeCodeCamp: FreeCodeCamp offers free blockchain development tutorials on their YouTube channel. The Solidity, Blockchain, and Smart Contract Course – Beginner to Expert Python Tutorial is a comprehensive video tutorial that covers the fundamentals of Solidity programming and blockchain development.
• CryptoZombies: CryptoZombies is an interactive, hands-on learning platform that teaches Solidity programming through the creation of a zombie-themed game. It offers a fun and engaging way to learn smart contract development, making it ideal for beginners.

2. Learning Platforms and Communities

Engaging with learning platforms and communities can provide you with valuable resources, support, and networking opportunities. Some notable platforms and communities for blockchain developers include:

• Ethereum.org: The official Ethereum website offers extensive documentation, guides, and tutorials for developers. It covers a wide range of topics, from the basics of Ethereum and smart contracts to advanced topics like scaling solutions and security best practices.
• Hyperledger Documentation: If you are interested in enterprise blockchain development, the Hyperledger Documentation is a valuable resource. It provides comprehensive guides and tutorials for various Hyperledger projects, such as Hyperledger Fabric and Hyperledger Sawtooth.
• Reddit r/ethdev and r/solidity: Reddit has active communities for blockchain developers, such as r/ethdev and r/solidity. These subreddits are great places to ask questions, share knowledge, and stay up-to-date with the latest developments in the Ethereum ecosystem.
• Discord servers: Many blockchain projects and communities have their own Discord servers where developers can connect, collaborate, and seek help. Some popular developer-focused Discord servers include the Ethereum Discord, Solidity Discord, and OpenZeppelin Discord.

3. Books and Publications

Books and publications offer in-depth knowledge and insights into blockchain technology and development. They provide a more comprehensive understanding of the underlying concepts and best practices. Some recommended books for blockchain developers include:

• “Mastering Ethereum” by Andreas M. Antonopoulos and Gavin Wood: This book is considered the definitive guide to Ethereum development. It covers the fundamentals of Ethereum, smart contract programming with Solidity, and building decentralized applications.
• “Blockchain Basics” by Daniel Drescher: This book provides a clear and accessible introduction to blockchain technology, explaining its core concepts, mechanisms, and potential applications.
• “The Blockchain Developer” by Elad Elrom: This book offers a practical guide to blockchain development, covering topics like Ethereum, Hyperledger Fabric, and Corda. It includes real-world examples and hands-on exercises to reinforce the concepts.

In addition to books, staying informed about the latest trends and developments in the blockchain industry is crucial. Following industry publications like CoinDesk, Decrypt, and Cointelegraph can help you stay up-to-date with the latest news, insights, and analysis.

4. Hands-on Projects and Hackathons

Hands-on experience is essential for mastering blockchain development. Engaging in projects and hackathons allows you to apply your knowledge, collaborate with others, and build a portfolio of work. Here are some ways to gain practical experience:

• Participate in blockchain-focused hackathons: Hackathons are events where developers come together to build projects within a short timeframe. Participating in blockchain-focused hackathons like the ETHGlobal events or the Chainlink Virtual Hackathon can help you sharpen your skills, network with other developers, and potentially win prizes.
• Contribute to open-source blockchain projects: Open-source blockchain projects on platforms like GitHub provide an excellent opportunity to learn from experienced developers and contribute to real-world projects. You can start by exploring projects related to Ethereum, Hyperledger, or other blockchain platforms that interest you.
• Build your own blockchain-based applications or decentralized apps (dApps): Building your own projects is a great way to solidify your understanding of blockchain concepts and showcase your skills. Start with simple projects like a basic smart contract or a token-based application, and gradually work your way up to more complex dApps.

By leveraging these resources and actively engaging in hands-on projects, you can accelerate your learning and gain the practical experience needed to succeed as a blockchain developer. Remember, the blockchain ecosystem is constantly evolving, so it is important to stay curious, keep learning, and adapt to new technologies and best practices.

Navigating the Blockchain Security Landscape

As a blockchain developer, understanding the security landscape is crucial for building robust and resilient applications. In this section, we will explore the fundamental aspects of blockchain security, common vulnerabilities and threats, and best practices that developers should follow to ensure the security of their blockchain projects.

Blockchain Security Fundamentals

Blockchain technology has revolutionized the way we think about security in the digital world. Its decentralized nature, cryptographic principles, and consensus mechanisms provide a robust foundation for secure transactions and data storage. Let’s explore these fundamental aspects in more detail:

1. Decentralized Nature: The decentralized architecture of blockchain networks makes them more resilient against attacks targeting a single point of failure. Even if some nodes are compromised, the network can continue to function securely, as highlighted in the Blockchain Security Overview by Chainalysis.
2. Cryptographic Principles: Blockchain relies heavily on cryptographic techniques, such as hash functions, digital signatures, and encryption, to ensure the security and privacy of transactions. These principles help maintain the integrity of the stored information and prevent tampering, as explained in What Is Blockchain Security? by IBM.
3. Consensus Mechanisms: Consensus mechanisms, such as Proof of Work (PoW) and Proof of Stake (PoS), ensure that all participants in the network agree on the state of the ledger. They prevent double-spending and maintain the integrity of the blockchain, as discussed in Blockchain Security: Common Vulnerabilities and How to Protect Against Them by Hacken.

Key Blockchain Security Vulnerabilities and Threats

While blockchain technology offers a strong security foundation, it is not immune to vulnerabilities and threats. Developers must be aware of potential weaknesses at the protocol, smart contract, and infrastructure levels:

1. Protocol-Level Vulnerabilities: Protocol-level vulnerabilities target the underlying consensus mechanisms and network architecture. Examples include 51% attacks, selfish mining, and eclipse attacks, as outlined in Blockchain Vulnerabilities and Attacks by Yeshwanth N on LinkedIn.
2. Smart Contract Vulnerabilities: Smart contracts can introduce vulnerabilities if not properly designed and audited. Common issues include reentrancy attacks, integer overflow/underflow, and unhandled exceptions, as mentioned in Addressing Security Concerns In Blockchain Gaming by Forbes.
3. Infrastructure and User-Level Threats: Blockchain security extends beyond the protocol and smart contract levels. Infrastructure and user-level threats, such as phishing, malware, and insecure key management, can compromise the security of blockchain assets, as discussed in Blockchain Security: Common Vulnerabilities and How to Protect Against Them by Hacken.

Blockchain Security Best Practices for Developers

To mitigate vulnerabilities and ensure the security of blockchain applications, developers should adopt a proactive and comprehensive approach. Here are some key best practices:

1. Secure Software Development Lifecycle (SDLC): Integrating security into every stage of the SDLC is crucial for building secure blockchain applications. This includes threat modeling, secure coding practices, code reviews, and thorough testing, as outlined in Blockchain Security Best Practices by Victoria Arkhurst on LinkedIn.
2. Smart Contract Auditing and Verification: Conducting comprehensive smart contract audits and applying formal verification techniques can help identify and fix vulnerabilities. Automated tools and manual review techniques should be used to ensure thorough coverage, as discussed in Blockchain Audit: L1 & L2 Protocol Security Analysis by Hacken.
3. Robust Key Management: Secure key management is critical for protecting blockchain assets. Best practices include using hardware security modules (HSMs) for key storage, implementing multi-signature wallets, and applying granular access control mechanisms, as explained in Blockchain.com Security.
4. Comprehensive Security Monitoring and Incident Response: Continuous monitoring and effective incident response are essential for detecting and mitigating security incidents. Developers should implement comprehensive security monitoring solutions, develop and test incident response plans, and conduct thorough forensic analysis, as outlined in Blockchain Security Best Practices for Businesses and Individuals by 101 Blockchains.
5. Compliance with Security Standards and Regulations: Adhering to industry-specific security standards and regulations, such as the Cryptocurrency Security Standard (CCSS) and regulatory compliance requirements (e.g., GDPR, AML/KYC), is crucial for ensuring the security and compliance of blockchain applications, as discussed in Information Security Compliance and the Blockchain by StandardFusion.

By understanding the blockchain security landscape, being aware of potential vulnerabilities and threats, and implementing robust security best practices, developers can create secure and resilient blockchain applications. As the blockchain ecosystem continues to evolve, staying informed about the latest security developments and collaborating with the community will be essential for navigating the ever-changing security landscape.

Leveraging Ethereum for Decentralized Application Development

Ethereum, the brainchild of Vitalik Buterin and Gavin Wood, has emerged as a groundbreaking decentralized, open-source blockchain platform since its inception in 2015. As the second-largest cryptocurrency after Bitcoin, Ethereum represents about 20% of the $1.1 trillion global crypto market, according to Forbes.

Unlike Bitcoin, which primarily serves as a virtual currency and store of value, Ethereum is designed to be much more. The Ethereum platform enables the creation and execution of smart contracts and decentralized applications (dApps), allowing users to conduct various financial transactions on its blockchain network. Ethereum’s native cryptocurrency, Ether (ETH), powers the network and is used to pay for transaction fees and computational services.

The Ethereum platform is built on the following key features:

1. Decentralized network: The Ethereum blockchain is decentralized, with all participants holding an identical copy of the ledger, allowing them to verify and record transactions.
2. Programmable blockchain: Ethereum is designed to be a programmable blockchain, allowing developers to build and run distributed applications using smart contracts written in programming languages like Solidity.
3. Smart contracts: Ethereum enables the creation and execution of self-executing contracts, where the terms of the agreement between buyer and seller are directly written into lines of code.
4. Decentralized applications (dApps): The Ethereum network can be used to host and run decentralized applications, giving users more control over their data and open access to the applications.

According to AWS, the Ethereum Virtual Machine (EVM) is the execution environment on the Ethereum blockchain, where all nodes run the EVM as part of the block verification protocol to keep the ledgers in sync. This allows Ethereum to offer a flexible platform for building decentralized applications using the Solidity scripting language and the EVM, with a rich ecosystem of developer tools and established best practices.

Ethereum utilizes a proof-of-work (PoW) consensus mechanism, which is being gradually transitioned to a proof-of-stake (PoS) model to improve scalability and energy efficiency. In 2022, Ethereum completed the transition to PoS, reducing its carbon footprint by up to 99.9%, as reported by Forbes.

The Ethereum platform supports a wide range of decentralized applications, including:

• Decentralized Finance (DeFi): Ethereum’s DeFi ecosystem has over $13 billion worth of value locked in its smart contracts, allowing for the development of financial services without the need for traditional financial institutions, according to Tenup Soft.
• Non-Fungible Tokens (NFTs): Ethereum provides a platform for creating and trading unique digital assets like art, collectibles, and real estate through NFTs, which establish verifiable ownership of these digital items.
• Decentralized Exchanges: Ethereum enables the creation of decentralized exchanges, allowing users to trade cryptocurrencies and other digital assets without the need for a centralized authority.

As the Ethereum ecosystem continues to grow and evolve, with upcoming upgrades like Ethereum 2.0, the platform is poised to offer even more opportunities for developers and users alike, cementing its position as a leader in the blockchain space.

Opportunities for Ethereum Platform Developers

The Ethereum platform offers a wealth of opportunities for developers looking to build decentralized applications and contribute to the growing blockchain ecosystem. With its robust programming languages, diverse development tools, and thriving community, Ethereum has become a go-to platform for developers worldwide.

Programming Languages: Solidity and Vyper

Solidity, the primary programming language for Ethereum smart contract development, boasts a robust developer community, extensive documentation, and a proven track record. According to Chainlink, Solidity is the most widely used language in Web3, offering developers more libraries, tooling, documentation, and support. Its syntax, similar to JavaScript, makes it an accessible starting point for developers transitioning to Web3.

Vyper, a Python-inspired language, provides an alternative to Solidity for Ethereum developers. Designed to be more readable and auditable, Vyper is the second most widely used Web3 programming language for EVM-compatible blockchains, as reported by Chainlink. Its simple language and compiler implementation help with code readability and auditability, making it easier to build secure smart contracts.

Diverse Development Tools and Frameworks

Ethereum offers a wide array of development tools and frameworks, catering to developers with different backgrounds and preferences. Some notable tools include:

• Foundry, Hardhat, Ape, and Web3j: These tools facilitate Ethereum application development, testing, and deployment, as listed on the Ethereum.org website.
• Front-end communication APIs: Web3.js, Eth.js, and Ethers.js enable developers to build Ethereum-powered applications with ease.
• Backend communication APIs: Web3.py, Web3.php, and Web3j allow developers to interact with the Ethereum network using their preferred programming languages.

Decentralized Application (dApp) Development

The Ethereum platform provides developers with the opportunity to build a wide range of decentralized applications, leveraging smart contracts and the blockchain’s transparency and security. Some potential use cases include:

• Decentralized Finance (DeFi): Ethereum enables the creation of smart contract-powered applications for loans, stablecoins, and decentralized exchanges, as highlighted by Medium.
• Non-Fungible Tokens (NFTs): Developers can create unique digital assets, such as art, collectibles, and real estate, on the Ethereum platform, establishing verifiable ownership through NFTs.
• Decentralized Exchanges: Ethereum allows developers to build decentralized exchanges, enabling users to trade cryptocurrencies and other digital assets without relying on a centralized authority.

Ethereum Ecosystem Growth

The Ethereum ecosystem is rapidly expanding, with a growing community of developers, enthusiasts, and stakeholders contributing to its development and adoption. Developers have the opportunity to:

• Contribute to open-source projects: Ethereum’s open-source nature encourages collaboration and innovation, allowing developers to contribute to various projects and protocols built on the platform.
• Participate in hackathons: Ethereum-focused hackathons provide developers with a platform to showcase their skills, collaborate with others, and potentially earn rewards for their innovative solutions.
• Collaborate with the broader Ethereum community: Engaging with the Ethereum community through forums, social media, and events can help developers stay informed about the latest developments, share knowledge, and build valuable connections.

As the Ethereum platform continues to evolve and mature, the opportunities for developers are only set to grow, making it an exciting time to be part of this transformative ecosystem.

Navigating the Regulatory and Compliance Landscape

As the Ethereum platform continues to grow and attract more developers, navigating the regulatory and compliance landscape becomes increasingly important. Developers must be aware of the challenges and considerations that come with building applications on a decentralized platform like Ethereum.

Regulatory Challenges

One of the primary challenges facing Ethereum developers is the lack of a unified regulatory framework. Cryptocurrency regulations vary significantly across different jurisdictions, making it difficult for developers to ensure compliance when building applications that span multiple regions. As highlighted in a Medium article, the decentralized nature of the Ethereum blockchain poses challenges for regulators seeking to enforce compliance standards, leading to debates on striking a balance between innovation and regulation.

Another regulatory challenge revolves around the legal status of smart contracts and the categorization of tokens. Developers must navigate the distinction between utility tokens and security tokens, as the latter are subject to more stringent regulations. The rise of Initial Coin Offerings (ICOs) and Security Token Offerings (STOs) on the Ethereum platform has been met with regulatory scrutiny, further complicating the compliance landscape for developers.

Compliance Considerations

Ethereum-based projects are under pressure to implement robust Know Your Customer (KYC) and Anti-Money Laundering (AML) procedures to comply with increased regulatory focus on combating financial crimes. Decentralized applications (DApps) and decentralized exchanges (DEXs) face challenges in adhering to these compliance requirements while maintaining user privacy and the pseudonymous nature of blockchain transactions.

Data protection and cybersecurity are also critical compliance considerations for Ethereum developers. With the implementation of regulations like the General Data Protection Regulation (GDPR), developers must ensure that their applications handle user data in a secure and compliant manner. The World Economic Forum’s Blockchain Toolkit highlights the importance of addressing data protection and cybersecurity concerns when establishing an Ethereum-based network.

Industry Collaboration and Self-Regulation

To navigate the complex regulatory landscape, the Ethereum community and industry stakeholders are actively engaging with regulators to foster collaborative solutions. By working together, they aim to establish industry standards and best practices that enhance compliance within the Ethereum ecosystem.

Self-regulation initiatives, such as the creation of guidelines for token sales and the development of standardized KYC/AML processes, demonstrate the community’s commitment to promoting a compliant and sustainable ecosystem. As mentioned in the Medium article, these collaborative efforts between the Ethereum community and regulatory bodies are crucial for bridging the gap and ensuring security within a legal framework.

Evolving Regulatory Landscape

Governments and regulatory bodies are gradually responding to the challenges posed by Ethereum and cryptocurrencies. While some jurisdictions have taken a more progressive approach, others have adopted a more cautious stance. Developers must stay informed about the evolving regulatory landscape and be prepared to adapt their applications accordingly.

The Ethereum community plays a vital role in shaping the regulatory future of the platform. Developers have the opportunity to contribute to the ongoing dialogue between the Ethereum community and regulators, sharing their insights and experiences to help craft sensible and effective regulations that foster innovation while ensuring compliance.

As the regulatory landscape continues to evolve, Ethereum developers who stay informed, engage with the community, and prioritize compliance will be well-positioned to navigate the challenges and seize the opportunities that lie ahead.