What does Idempotent mean

Idempotent means doing something again and again has the same result as doing it once.

Imagine you have a toy box, and every time you press a button on your remote, it adds one more red car to the box. If you press the button once, you get 1 red car. Press it twice, you get 2 red cars. That’s not idempotent, each press changes the result.

But now imagine a magic (okay, maybe it is magic) button that adds a red car only if it's not already there. You press it once: 1 red car. Press it again: still 1 red car. Press it a thousand times: still 1 red car. That’s idempotent, no matter how many times you do it, the result stays the same.

Sometimes, when you click “Save” on your tablet or phone, it might save your work even if you clicked it multiple times. That's idempotent, your work is saved once, and clicking again doesn’t change anything else. Like pressing that magic button, it still works, but it doesn't add extra red cars (or extra saves).