User experience: how people understand, use and feel about a product or service across a task.
A practical example
A visitor can find relevant information, understand the offer and complete an enquiry without unnecessary obstacles.
What to watch for
A visually attractive page can still have poor UX. Use research, accessibility checks and real task completion to judge the experience.
Related reading
Explore User Interface (UI) and Mobile-Friendly Website. See how this fits into Web design.