A touch-up is a small amount of paint applied to fix a scratch, scuff, or thin spot in a finished surface. Saved paint from the original job keeps touch-ups color-matched, which is one reason we label and set aside paint at the end of a project.
Touch-up work rewards restraint. Feathering the repaired spot into the surrounding coat and using the same sheen keeps the fix invisible, while over-brushing spreads the repair into something more noticeable than the original flaw.