An MMO, or Massively Multiplayer Online game, is a type of video game that allows a large number of players to interact with each other in a virtual world. These games often feature expansive environments, quests, and character customization, enabling players to explore, battle, and collaborate with others from around the globe. MMOs can be categorized into various genres, such as MMORPGs (Massively Multiplayer Online Role-Playing Games) and MMOFPS (Massively Multiplayer Online First-Person Shooters). Popular examples include World of Warcraft and Final Fantasy XIV, which offer immersive experiences and social interactions among players.