Who is the Illustrator? Do you know what an illustrator is?

Today I was reading Dr.Suess books. I read 3 of them - Hop On Pop, Old Hat New Hat and There is a locket in my pocket. The pictures were so funny and both mom and I were laughing as I was reading to her and showing her the images. Then I looked at my mom and asked, "Who is the illustrator of this book?" My mom was surprised that I knew what an illustrator means. We turned together to look at the front page and did not find the illustrator. So we asked google and found out that Dr.Suess did his own illustrations. 

Now what exactly is an illustrator? I know, do you know?

An Illustrator is a person who draws or creates pictures for magazines, books, advertising, etc.

In the picture below the two pups are hopping on their pop(dad)!