A distributed ledger is usually a database that is composed of all transactions that are constantly updated. It comprises many blocks, each containing at least one transaction. The blocks are joined together to form a chain using cryptography. This, therefore, leads to the blocks containing the cryptographic identifiers of the previous block. It is often referred to as a type of blockchain or an open, distributed ledger.
This type of technology has been around for a while but its usage has increased in the last couple of years because it can be applied to many different fields, such as cryptocurrency transaction public ledgers, digital asset registries like the blockchain which records all bitcoin transactions or even voting websites.