Usable

A usable product lets people get things done easily, without confusion or extra effort. Usability is not about whether a product can do something, but how easily people can do it.

Small details add up. When someone types a card number, a number keypad saves them from hunting for digits on a full keyboard. Clear buttons, a way to go back and short forms help in the same way.

Pro tip: watch for moments when people hesitate or tap the wrong thing. Each one is a usability problem worth fixing, even if the person succeeds in the end.