Player versus environment

From GuildWiki

Player versus environment (or PvE, sometimes player versus monster, or PvM), is a gameplay distinction, in contrast with player versus player (short: PvP) gameplay.

Player versus Environment is a type of gameplay common to RPGs in general. This is where the character engages in combat with AI-controlled computerized opponents, as opposed to PvP, where he engages with human players as opponents.

In Guild Wars, PvE content is only available to roleplaying characters. In PvE gameplay, your primary purpose (aside from fun, obviously) is to "grow" your character, gain experience, learn skills, acquire better weapons and armor, etc. This is done mainly by completing quests and missions, and by venturing into explorable areas to fight monsters.