User onboarding is the process of orienting and familiarizing a first-time user with the environment of your product, giving basic essential directions that will increase the likelihood that new users will continue to use your product or service.
Did you ever have to put aside a project to respond to the 15th revision request from a client? Being the professional you are, you'll keep working until your client will be satisfied. Yet, who has so much time?
It's pretty hard to come by a design that equally serves both beauty and function. This applies to logo design, website design, illustrations, posters, and almost anything that has lines, curves, colors, and is artwork.