“UI is the saddle, the stirrups, & the reins. UX is the feeling you get being able to ride the horse.”
— Dain Miller, Web Developer
User Experience Design involves research, communication, sketching, artifact creation, visual design, usability testing and various other techniques to help create a great product.
A related discipline, User Interface Design, means using layout, branding, the right visuals, current standards, and optimal coding techniques in HTML, CSS, Javascript and other languages to build the interface.
This is how the UX and UI landscape has traditionally looked:
Nowadays, the rapid growth of Agile development methods has resulted in smaller development teams working on projects in short timeframes called sprints. Companies often include a single UX designer on each Agile team, resulting in the need for UX designers to manage the visual design themselves. Such companies look more like this: