Some text from Minecraft Wiki used under Creative Commons Attribution-Share Alike License 3.0
|First Appearance||Infdev (Secret Friday Update 2)|
|Type of Block||Solid Block|
|Data Values||Hex: 32 Dec: 52|
A Mob Spawner will create Mobs provided there is space for the Mob to be generated and the light level within the spawning radius remains below seven. Mobs are created within an 8x8x3 high area centered on the spawner Block's lower northwest corner. Note that mobs can spawn in any dark space within range, even if the spawner is fully lit. The spawner will only spawn Mobs if the player is within 16 blocks of it. A common trend among seasoned players is to create Mob traps around Mob Spawners for an easy way to gather that Mob's resources.
Note: Monster Spawners can also be obtained through mods and hacks, such as TooManyItems. They cannot be obtained when mined by an item with the Silk Touch enchantment. They can also be obtained with /give.
Spawners can be used to make very effective Mob grinders, as they spawn more Mobs faster when a player is in the vicinity. The best way is make a large dark room around the spawn, and place the floor 3-5 blocks below. On the floor place Water to funnel the mobs that will spawn into a drop in the floor, which will lead wherever the player wants. Once they are all gathered in the desired location, the player can kill them manually or with a Redstone contraption and harvest the experience as well as the items.