"An illustration is a decoration, interpretation or visual explanation of a text, concept or process, designed for integration in published media, such as posters, flyers, magazines, books..." [Wikipedia]
Much of my career was funded by graphic design projects intended for advertising and marketing of a variety of products, magazine, books, corporate branding, signage, and web design.
Computer illustration or digital illustration is the use of digital tools to produce images under the direct manipulation of the artist, It is also distinct from digital manipulation of photographs, in that it is an original construction "from scratch".
This gallery displays a range of both, although by definition the once distinct difference in description has become somewhat blurred, and using the term illustration to label both areas of artistic output is commonly accepted. I personally use the term "photo illustration" to differentiate.
Working as a commercial artist requires a wide set of skills. More so when one, as myself, works primarily as a freelancer. If one is limited to a single area of expertise, many potential client projects that fall outside the artists skillset would not even be considered.
Web design, for example, is one of the areas I spent a great deal of time learning. Writing code couldn't be more different that the creation of art. It is distinctly mathematical in nature, but I found it to be an integral part of having complete control over presentation, and distribution, of an artists completed works.
This web site is an example; I developed this site using a BootStrap framework, css, and just a bit of jQuery scripting. Working in code is an art in and of itself.
The concept of being able to offer my product and services online, without the restrictions of a physical storefront, allowed me to have more time to create, and this personal web site first went online in 1994.