Iteration
A repeated design cycle focused on refinement through feedback rather than a single final pass.
In practice
Iteration means working in repeated cycles: make a version, test or review it, learn, and make a better one. Instead of perfecting a single design in isolation, a designer might make a rough checkout screen, watch three people try it, fix what confused them and test again. Each round costs less when versions are rough, which is why early iterations are often sketches or paper.
Often confused with Prototype
Iteration is the repeated cycle of improving a design; a prototype is one testable version used within that cycle.
Try this
Sketch a logo idea, show it to a friend, change one thing based on their reaction, and repeat three times.