A mistake is when you make a decision that you think was not your best choice.  There are two types of mistakes: betting mistakes and non-betting mistakes.  Examples of betting mistakes are not folding before the flop when you think you should have, and calling on the river when you think you shouldn’t have.  Examples of non-betting mistakes are when you play too long according to you, or when you play underfunded according to you, or when you say the wrong thing according to you.