When we're talking about the type, typically we are referring to the composition of an asteroid, and they're primarily divided into three categories. Firstly, the C-type asteroid, which is made from silicate and clay rocks. Secondly, the S-types, which are made from silicate and nickel-iron. Finally, the M-types, which are primarily made of nickel-iron. There are more types of asteroid than these, but these are the most common.