See also #usable.
Definitions: The user experience (UX) is how a user interacts with and experiences a product, system or service. It includes a person’s perceptions of utility, ease of use, and efficiency. Improving user experience is important to most companies, designers, and creators when creating and refining products because negative user experience can diminish the use of the product and, therefore, any desired positive impacts; conversely,
User experience includes all the aspects of the interaction between the end-user with the company, its services, and its products.
Derived from Wikipedia/User-Experience
User-Experience is usability + graphic-design + accessibility