In Minecraft, a mob farm is a structure designed to spawn and kill large groups of mobs for the purpose of collecting loot, experience points (XP), and mob drops.
There are many different types of mob farms, but one of the most efficient and reliable is a spawner-based mob farm. This type of farm utilizes a mob spawner, a block that naturally spawns mobs when a player is nearby. By building a mob farm around a spawner, players can create a constant source of mobs to kill.