What is web design?

HTML + CSS + JavaScript + Text + Images + Etc.

Wikipedia states:

Web design is a broad term covering many different skills and disciplines that are used in the production and maintenance of websites.[1]

The different areas of web design include:

Often many individuals will work in teams covering different aspects of the design process, although some designers will cover them all.[2]

The term web design is normally used to describe the design process relating to the front-end (client side) design of a website including writing mark up, but this is a grey area as this is also covered by web development.

Web designers are expected to have an awareness of usability and if their role involves creating mark up then they are also expected to be up to date with web accessibility guidelines.

Source: Wikipedia.