Blockchain is the fundamental technology behind cryptocurrencies. It enables people to transfer value online by distributing digital information, but not copying it.
Blockchain is a ledger – a list of records that link together using cryptography. These records are called “blocks,” and they join to form a “chain,” hence the name “blockchain.” This is a new, permanent, and secure way of storing information, and it has applications beyond cryptocurrencies. For more information on blockchain read this article.