What is a Digital Ledger?
A distributed ledger (also called a shared ledger, or distributed ledger technology, DLT) is a consensus of replicated, shared, and synchronized digital data geographically spread across multiple sites, countries, or institutions
The blockchain is a shared public ledger on which the entire Bitcoin network relies. All confirmed transactions are included in the block chain. This way, Bitcoin wallets can calculate their spendable balance and new transactions can be verified to be spending bitcoins that are actually owned by the spender.
In simple words, Ledger is just like a Book with all the transactions ever made are there in this book and this book is distributed to everyone across the world who has any sort of digital assets.