Blockchain is a technology that allows for the creation of scarce, transferable digital assets. It is a ledger that handles the “double spend” problem of accounting/economics for digital assets. Blockchains are…

Networks

A blockchain is a network of computing machines that connect together and create a computing system that can power an array of applications.

Database / Ledgers

A blockchain is a distributed database that maintains a continuously-growing list of records called blocks.

Each block contains a timestamp and a link to a previous block. The data in a block cannot be altered retrospectively.

Decentralized

A blockchain ledger is not stored in one (central) computer or database. Each network participants maintains a copy of the latest state of the ledger.

Blockchains are often called decentralized or distributed because the records and blocks are confirmed by the multiple network participants, so all parties can agree on the shared dataset and no single party has complete authority.

Secure & Verifiable

Blockchain allows information to be updated, verified, and shared securely—not copied like traditional databases.

For example, if you were to send an email with a file attached, the recipient would not be getting the exact attachment. Instead they would be getting a copy. But how do either of you know if that data is accurate or hasn’t been changed since you have two copies? How can you be sure of its verified accuracy?