Why is it called a "bank balance"?

When describing how much money is in a bank account, we'll often say that the account "has a balance" of a certain amount, as in:

Your bank balance is currently £13,550.

Why do we describe this as a "balance", though? If anything, it seems like an account imbalance, because more money has been paid into the account than has been taken out. The only time an account would be "balanced" is if it was at zero. So why the term "bank balance"?

Balance does not only mean that two sides are equal, but it can be the result of "balancing", meaning to compare all the items on one side to those on the other side.

In this case, your bank balance is the result of adding up all the incoming transactions, and deducting all the outgoing transactions.

The resulting balance may be positive or negative.

If you make up the balance of a project, you evaluate what went well, and what didn't, and you come to an overall conclusion about the project's success.

An 'account' within the records of a bank or any other business is part of a system of double-entry bookkeeping, originated by the Venetians.

The beauty of a double-entry system, which is used almost by every business everywhere in the modern world, is that it carries an inherent check for errors. At any one time all debit balances must equal all credit balances. If they do not, then there has been some sort of error, which needs investigation.

If all debits equal all credits the books are said to 'balance'.

So why is it that an individual account has a 'balance'? Because if you add all the debits to that account and subtract all the credits, the resulting figure, debit or credit, is the one that is needed to 'balance' one side with the other.

Nowadays it is all made easy by computers doing the legwork. But anyone, like me, who began as a trainee accountant in 1961 will remember what it was like having to 'balance' a set of books manually. It could be positively mind-numbingly infuriating if they didn't agree and could involve a lot of sweat, midnight-hours, black coffee, and for some (not me) cigarettes, to find the error(s). 'Balance' was a word at the centre of one's life.