What is UX
There is of course no easy answer to a field that has sprung out of arts, psychology and even computer science. But, let’s try.
User Experience (UX) is a term for a user's overall satisfaction level when using your product or system. If it is a good experience, they're happy. If it is a bad experience, your users do not come back. And then they tell their friends ...
We also abbreviate User Experience Design, the field and processes, as UX.
Wikipedia, 1 January 2011
User experience design is a subset of the field of experience design that pertains to the creation of the architecture and interaction models that impact user experience of a device or system. As user experience is a subjective feeling, it cannot actually be "designed". Instead, you can design for a user experience, trying to enable certain kind of experiences. The scope of the field is directed at affecting "all aspects of the user’s interaction with the product: how it is perceived, learned, and used."
The general consensus is that user experience is the umbrella term that encompasses a wide array of interface-related fields. The three biggest fields are information architecture (IA), interaction design (IxD) and user research. Most organizations see visual design as a big part of UX as well.
The user researcher role, focuses on methods for user research and usage testing, both with and without users, to provide insights about the system.
User Research and Modelling
The information architect role is often described as the librarian of UX. It involves a lot of categorizing and organizing the content of the system.
Taxonomies and Vocabularies
The interaction designer role, quite often also an interface designer, concerns all aspects of a user’s interaction with the system, its behaviour and crafting a workflow that covers all aspects of this.
As a UX designer or as a part of the UX design team, you need to be both information architect, interaction designer and user researcher.
Another big part (and perhaps role) of UX is accessibility, i.e. focus on people with disabilities and their right of access to the system. This role tends to be less creative than the designer role, aligning on measuring and modelling.
Some people have other fancy titles, such as usability expert, UX architect or UI designer/developer. These architects/experts probably do a lot of high-level, strategic work related to UX. A designer/developer will probably be more hands on in implementing the actual interface solution itself.
All of these roles are obviously overlapping, both in time and in methods, e.g. information architects and interaction designers should of course do user research as well. It is called about the User Experience, after all.