An illustrator is a graphic artist who specializes in enhancing writing by providing a visual representation that corresponds to the content of the associated text. The illustration may be intended to clarify complicated concepts or objects that are difficult to describe textually, or the illustration may be intended for entertainment, as in greeting cards, or cover art or interior art for books and magazines, or for advertisement, as on posters.

Most contemporary illustrators make their living creating artwork for use in children's books, advertising, newspapers and magazines. Pen and ink and airbrush artists traditionally dominated this realm.

Computers dramatically changed the industry, and today computers are used to produce most of the commercial illustrations.

However, traditional illustration techniques are still popular, particularly in the field of book illustration. Watercolor, oil painting, pastels, wood-engraving, linoleum cuts, and pen and ink are some of the traditional techniques used by successful exponents of the art.

There are no formal qualifications needed to become an illustrator. However, many established illustrators attended an art school or college of some sort and were trained in different painting and drawing techniques. Art Colleges and Universities now offer specific courses in illustration.

Many illustrators are freelance, commissioned by publishers (of newspapers, books or magazines) or advertising agencies. Most of the scientific illustrations and technical illustrations are also known as information graphics. Among the information graphics specialists are medical illustrators who illustrate human anatomy, often requiring many years of artistic and medical training.