Version 2 or above do not allow for mods that change the main.scm, script.img, gta3.img, or other. Most shops will not sell this version anymore. V1 is the original version of the game, which was hit by the Hot Coffee fiasco. This is the best platform to mod, and the easiest. There are several different versions of San Andreas, including console versions and multiple PC versions: There are many different types of mod, and a wide variety too. A typical San Andreas mod could be changing a car, for example changing the Bullet into a McLaren F1, or changing the AT-400 into a Boeing 747.
We're talking about San Andreas, but you can get mods for many other games. A mod is a modification to a game or piece of software.
