meteoroid -- a tiny space rock (usually a speck of debris from a comet or asteroid) while it is in space or flying through Earth's atmosphere

meteor -- a streak of light in the sky caused by a disintegrating meteoroid

meteorite -- a rock from space that hit the ground because it did not burn up entirely in the atmosphere.

Asteroid Classes:

C-type -- includes more than 75% of known asteroids: extremely dark (albedo 0.03); similar to carbonaceous chondrite meteorites; approximately the same chemical composition as the Sun minus hydrogen and helium.

S-type -- 17% of all main-belt asteroids: relatively bright (albedo .10-.22); metallic nickel-iron mixed with iron- and magnesium-silicates;

M-type -- most of the rest: bright (albedo .10-.18); pure nickel-iron. There are also a dozen or so other rare types.