My son responds:
Gandalf is a Miar. If you have never heard of the Miar, Valar, or even Iluvitar, they all live acrosss the Sea. Iluvitar made everything, he is the one greatest, his power goes on, and on, and on, (you get the picture). Valar are second in command. Miar are lower still. Gandalf was sent by Iluvitar to help Middle Earth (where Lord of the Rings was set). He is not allowed to actually physically fight Sauron, but he can assist others in doing so. Saruman is a Miar also, and he, Gandalf, Radagast (read LOTR to find out about him), and others make up the order of wizards: the Istari. By the way, Sauron was a Miar also, but was banished from the land across the Sea for assisting in evil deeds. I got all this from the Silmarillion, and Appendices in LOTR.