A salchow is a jump that takes off from a back inside edge and lands on the back outside edge of the other foot.
A loop is a jump that takes off from the back outside edge and lands on the same edge. A lutz is a jump that takes off from the back outside edge and lands on the back outside edge of the other foot. An axel is one of the most difficult jumps and the only jump that takes off forward. The axel is landed backward, so a "single" involved rotating in the air one and a half times, a "double" two and a half rotations, etc...
Click here to see a description of Michael's famous *QUAD LUTZ*.