Blockchain is decentralized and distributed database in the open source model in a peer-to-peer Internet network without central computers and without a centralized data storage space, used to record individual transactions, payments or accounting entries encoded with cryptographic algorithms. Blockchain is a public, anonymous, and verifiable register that anyone can access.

In other words, blockchain is simply a chain of blocks. In this context, a block is a digital information stored in a public database called a „chain”. Blockchain is a growing list of records which are linked using cryptography. Each block contains a cryptographic hash of the previous block, a timestamp, and transaction data. Blockchain records transactions between parties in a permanent and secure way. 

Bitcoin and Ethereum are one of the cryptocurrencies based on blockchain technology.