Swamp hut

Witch huts or swamp hut are generated structures that have the ability to spawn witches.

Generation
Witch huts generate in swamp biomes. However, they do not generate in the swamp hills biome variant.

Structure
Witch huts consist of a small square "hut" made of spruce wood planks, with oak log "pillars" extending down to the ground. There is a small platform outside of the hut that could be an entrance; however, it is many blocks above the ground, and there are no stairs that go upwards to the hut. The roof of the witch hut is made up of spruce wood stairs and spruce wood planks.

The inside of a witch hut consists of an empty cauldron, a crafting table, and a flower pot with a red mushroom in it. However, in Bedrock Edition, the cauldron generates with a random potion inside of it in random amounts. These potions include Swiftness, Slowness, Weakness, Healing, and Poison. Water Breathing and Fire Resistance seem to be excluded or have a very low chance of being spawned.

Mob spawning
The 7x9x7 area inside and outside the witch hut can only spawn witches and black cats. No other hostile or neutral mobs can spawn in this area, although passive mobs can. Additionally, one witch always spawns in each witch hut upon chunk generation.

Trivia

 * The "hut" part of a witch hut generates on or above the surface, while the wood "pillars" extend down until they reach solid ground. This means that if part of a witch hut is at sea level and another part is on top of deep ground, such as a ravine, the pillars on the deep-ground side will go all the way down to the ground.
 * It's possible for several witch huts to generate on top of one another.
 * Before 1.7.2, witch huts were the only place where witches had the ability to spawn.