Everything starts with an idea and that idea is brought to life by an artist. Like any idea in the world of media and entertainment you must first understand the story and it's characters, then you go straight to sketching. This requires hours of sketching and refinement until the artist captures the heart of the story. The next step is carefully inking (marker) all the sketches into a final image, then i scan it onto the computer and bring it to life with color.
There was a time before Disney went CG, they were known for their reliance on traditional artists, storyboards, and sketches. Have no fear, artists are still needed to sketch out a visual depiction, whether it be for animation, movies, or a video game. Even in the world of Disney and CG, sketching remains the quickest and most valued shorthand used to bring any idea to life.