To explain you very quickly, blockchain is a technology behind bitcoin. It works like a database for all Bitcoin transactions and it keeps all records since the first transaction.
A more detailed description of what blockchain and Bitcoin are is below.👇👇👇
A block chain or blockchain is a permissionless distributed database based on the bitcoin protocol that maintains a continuously growing list of transactional data records hardened against tampering and revision, even by operators of the data store's nodes. The initial and most widely known application of the blockchain technology is the public ledger of transactions for bitcoin and the inspiration of similar distributed ledgers known as altchains. Each blockchain record is enforced cryptographically and hosted on machines working as data store nodes
Bitcoin is a digital asset and a payment system invented by Satoshi Nakamoto who published the invention in 2008 and released it as open-source software in 2009. The system is peer-to-peer; users can transact directly without needing an intermediary.Transactions are verified by network nodes and recorded in a public distributed ledger called the block chain.