Idempotence

Idempotence is a way of saying that when you do something the same thing over and over again, the outcome will still be the same. An example of this would be if you had a water bottle with a lid on it. If you open the lid once, the outcome will be that the bottle is open. But if you open the lid twice, the outcome is still the same - the bottle is still open. The opening of the bottle is an example of an idempotent action - it doesn't matter how many times you open the lid, the result will always be the same.