https://www.techradar.com/news/what-is-blockchain-everything-you-need-to-know

Like much of the technology world, cryptocurrencies such as Bitcoin still rely on some form of database that are able to track large volumes of transactions and keep them secure. The solution used by many of the world’s largest digital currencies is the blockchain. 

First implemented in 2009, the technology consists of 'blocks' that hold batches of timestamped transactions, with each block linked to the previous one through cryptography, thus forming a chain.