The illustrator is a fine artist who illustrates for books, magazines, newsletters, websites, brochures, stamps, and any commercial item. An illustrator may work on a salary, freelance, or as a side job.
I once knew a young high school graduate who wanted to break into the business as an illustrator. He dropped by my agency and showed me his portfolio. I was very impressed and his price was right. (At the time, he only charged $20 an hour for his services) I used his illustrations for a client. Many saw his work and began to ask him to illustrate for their clients.
Soon he was in demand. To make a long story short, this young man is now making over $100,000 a year. Because he is self-employed, he takes vacation time whenever he feels like it. I'm not saying that anyone who enters this profession will have a fairy tale story ending like this one, but it should illustrate that the old saying, "starving artist" is no longer valid. Parents can no longer say to their kids, "Don't you want to get a real job?" If they say this, tell them, "Why should I when I can get $100,000 a year in salary and do what I enjoy?"
While working in a medium size ad agency in Chicago, I worked with an illustrator who was kept on salary there. He did quick illustrations that were included on instructions, packaging, and ads. He was making a fairly paltry $25,000 a year. On his first interview at another agency, he got a job as an illustrator for $60,000 salary. This was back in 1986, so I'm sure it's more now. I don't believe that an artist should focus on money- but with there being so much criticism of art careers lately, I have to point out a few falsehoods. There is money to be made in illustration.
Job titles in Illustration
(Salary range: $39,552 - $94,880) 
This person usually goes through a pre-med program in addition to art studies in college. Some art schools offer medical illustration as a major. A strong knowledge of anatomy and science is a prerequisite for this profession. Graduates from this profession may expect quick job placement. This illustrator creates drawings, paintings, diagrams, and models of medical or biological subjects in fields such as anatomy, histology, pathology, physiology, or in surgical procedures, for use in research, publications, exhibits, consultations, and teaching activities. The Medical Illustrator/Animator uses traditional image editing software, 2D, 3D animation and modeling software to build visual stories that are educational as well as relate to the health care needs of consumers. Artists may illustrate in medical journals such as JAMA, or for drug companies such as Eli Lilly, Merck, or Bristol-Myers Squibb. Some medical illustrators specialize in forensics and will often team up with law enforcement officials or attorneys in order to create a visual representation of wounds committed in crimes. Below you will find more resources for medical illustration.
Illustrators create original works of art for their aesthetic value, rather than a functional one. Illustrators work as freelancers or work in design firms or advertising agencies. Those who work in ad agencies create illustrations that are used in advertisements. In design firms they illustrate logos or anything that deals with the identity of a company.