9mm: The most popular and widely used worldwide.
.40 Caliber: Larger and slower than 9mm and has more recoil
.45 Auto: Slightly larger and slower than .40 caliber with slightly more recoil
.380: Popular self-defense caliber with a relatively short range
10mm: Powerful round that can be used for self-defense and hunting
.357: Very powerful self-defense and hunting round