As an illustrator, you would produce drawings, paintings or diagrams that help make products more attractive or easier to understand. This could include books, book jackets, greetings cards, advertisements, packaging and detailed technical diagrams.
In this job you will need good attention to detail. You will need creativity but you'll need to stick to a brief. You will also need to manage your time well, so you meet your deadlines.
Most professional illustrators have a degree, either in illustration or in another art-related subject. To get jobs, you will need to build up a portfolio (examples of your work), to show employers what you can do. If you work freelance you will usually use an agent to help you get work.