9mm Makarov ammunition is a classic cartridge in its own right. 9x18 Mak was developed by the Soviets for both their pistols and submachine guns. Makarov has served with various Russian police and military units since 1951 and has only recently starting waning in popularity.
These rounds were actually designed to be incompatible with the 9mm Luger (9x19) round simply as an in-case-of-war directive. This directive was put in place in case a war broke out, the 9mm Makarov would be incompatible with 9mm NATO rounds meaning ammunition could not be stolen from depots and then used by NATO enemies against the Soviet Union and her communist friends.
The 9mm Makarov round is also considered ballistically inferior to 9mm Luger. Makarov is capable of allowing pistols to be chambered in a simple and easier blow back configuration. This meant the pistols issued were easier to design, cheaper to build, and incredibly reliable.
That efficiency of production lead to pistols becoming quite popular in the United States after the fall of the Soviet Union. Once the Soviet Union collapsed a surplus of Russian firearms were released in the United States where civilian shooters could gobble up the pistols for $200-$300 at most gun shops. These handguns were very cheap on the U.S. market and the price point is what made them so popular. The 9mm Makarov round was also quite cheap and easy to find due to the amounts of surplus being imported from the former Soviet Union.
Today, you'll find an assortment of 9x18 Mak ammo for sale with the various bullet types listed below. Many of these rounds are still produced in the former Soviet Union and Ukraine, staying true to the roots of the cartridge.