Gnucash works on the principle of double-accounting, which means that each transaction in an account should be balanced in another account.
Money you received in your bank account must be balanced in an income account
, an paid invoice must be balanced in a expense account, a transfer between two accounts should be balanced from one account to another, etc.. This is the way that gnucash can subsequently make detailed reports
on income and expenses, as each transaction is methodically classified by you during the fiscal year.
If a transaction is to be divided among several accounts, this is called a transaction split