The process of constructing a world, originally an imaginary one
Developing all the little things a world consists of, and make them authentically fit together: this is Worldbuilding.
Worldbuilding with Concept Art
There are many different types of concept art, which can be used to create a particular part of the world. I have categorized the most common ones, even though there is no final agreement on what these image types are called. It does help to be on the same page, so this is my definition of them: