User experience (UX) is how a person feels when interacting with your website or your employees feel when they interact with your business applications. UX encompasses a lot of factors, some that are controllable by designers and developers and some that are environmental or just user preference. These factors include usability, accessibility, performance, design/aesthetics, utility, ergonomics, overall human interaction and marketing.
But UX is not exactly the same thing as usability, although they are closely related. UX is the experience, emotion, intuition and connection a user feels when using a site or product. Usability is more about the effectiveness of a site design and how user-friendly it is. Usability is a key component of the overall user experience. When working with and designing your user experience the usability aspects should be equally thought of during the process.