What are source and destination in a ledger?

Source and destination are the two sides of a ledger transfer. The source is where the value leaves. The destination is where it arrives. Every transaction has both. That pair is how a double-entry ledger records a movement without a one-sided post.

How do source and destination work?

You name two balances. The ledger debits one and credits the other for the same amount. The book stays in balance because the two sides are created together. There is no “just add money” call.

A deposit from a bank still has a source. That source is often an omnibus or a clearing balance that represents money you already hold, or money you are about to receive. The customer wallet is the destination.

Source and destination vs debit and credit

Debit and credit are the accounting names. Source and destination are the product names. They describe the same two-sided post. Developers who do not live in ledgers usually find source and destination easier to read on a money movement map.

Multiple sources or destinations

A split can pull from more than one source, or land in more than one destination. The rule does not change. The sum that leaves equals the sum that arrives. Each leg is still a two-sided post.

In Blnk every transaction requires a source and a destination. That is the double-entry rule, written as two balance ids. Draw those pairs on a money movement map before you post. Read double-entry for developers if you want the accounting version of the same idea.