What is a Beet?

Last night my young neighbor asked me What is a beet? I showed her. I said it looks like a clod of dirt but it is brightly colored under the skin. Then I brought out my potato beet salad for her to taste. Her two friends and her brother came over to see what was happening, and I gave them all forks. Help yourselves I said, holding the big pot over the fence. I am not afraid of germs.