Nether Brick is a common block found in the The Nether, and it makes up Nether fortresses.
They were added in the pre-release of Beta 1.9. As such, they are the only readily available source of strong building material in the Nether. Nether brick can also be used to make Nether Brick Fences. They can be crafted as of update 1.5.
Wither Skeletons can spawn on them as of snapshot 12w37a. It also seems to make areas darker.
|Nether Brick||Nether Brick Slab x6|
|None||Nether Bricks||Nether Bricks||None||None||None|
|None||Nether Bricks||Nether Bricks||Nether Brick||Nether Brick||Nether Brick|
|Nether Brick Stairs x4||Nether Brick Fence x6|
|Nether Brick||Nether Brick||None||Nether Brick||Nether Brick||Nether Brick|
|Nether Brick||Nether Brick||Nether Brick||Nether Brick||Nether Brick||Nether Brick|