The blockchain is a distributed ledger that verifies and stores the transactions of all bitcoin users. It’s essentially a database that maintains a record of all bitcoin transactions ever made, in chronological order. The blockchain stays up-to-date in real time. There are two types of blockchain – private, where only parties who have mutually agreed on the transaction can access it, and public, where anyone can read about the contents. Private blockchains are used by corporations for verifying stock ownership or corporate mergers. Public blockchains are used for bitcoin payments because it allows any user to verify payments without having to involve third parties in verification work or opening their personal financial information up to scrutiny.
Bitcoin miners verify new blocks on the network when they are created which includes paying fees to both the miner and the original sender of funds along with propagating old blocks throughout the network in an effort to help maintain its chronological integrity. Once these incentives are set into motion individuals will be incentivised to solve mathematical puzzles which ensures that old data is continually verified at various intervals throughout its existence without requiring too much work from both parties involved whenever there is interest generated in keeping things consistent.