Distributed ledger is defined as a system of independent computers that are simultaneously recording data. With distributed ledger technology, identical copies of the recording are kept by each computer.
We can define a distributed system, as one where all computers work independently toward the same goal as one large system. We can define a ledger as a book used to record transactions (money in, money out). However, distributed ledger technology has evolved beyond recording transactions so that it can record any data.
With distributed ledger technology, there is no central authority maintaining the system. Instead, updates to the ledger are independently created and then voted on. Once an agreement regarding the update has been reached, a recording is made in the ledger.
The latest version of the ledger, with the new recording, is then saved to each computing system and the process repeats itself.
The first type of distributed ledger technology is called the blockchain.