What are they?

• Little bodies (smaller than our moon) down to 1 km and less.
• C-type, S-type, M-type, and Basaltic

Where are they?

• Most between Mars and Jupiter. (2.8 AU predicted by the Titus-Bode Law.)
• Some at Jupiter's orbit (Trojans)
• A few further out and further in.

How did they arise?

• Original material unable to coalesce near Jupiter's strong gravity
• Not a whole lot of material to begin with - Jupiter took some?
• Repeatedly fracture into smaller asteroids, forming happy asteroid families.

And if you haven't yet, Read Chapter 12 in your book! (Asteroids)