A @blockchain is a distributed database that continuously grows with a record of all of the transactions that have occurred with a given cryptocurrency. This database is often referred to as a ledger because the data contains a large list of transactions that have taken place. In Monero, these transactions are packaged together into 'blocks' every 2 minutes (on average), and all miners and nodes on the network have copies of these blocks.
Unlike Bitcoin and other cryptocurrencies, transactions in the Monero @blockchain do not reveal where funds came from or went to, providing anonymity and making the currency completely @fungible. Additionally, the amounts of all transactions are hidden by @RingCT, a feature of Monero. For auditing or other transparency purposes a user can share a @view-key to prove they control certain amounts of Moneroj.