Netherrack

Netherrack (formerly known as Netherstone ) is the most abundant solid block in The Nether. When lit on fire, it burns indefinitely.

Usage
Netherrack can be used as part of a trapping mechanism for Mob farming. It can also be used to protect buildings or places from mobs, mob damage, or other players.

Netherrack is good for building functional structures, (Bridges, walls, etc.) but may look unsightly to some. If this is the case, use stone or another block type. Also, it has a low blast resistance, so its not good for explosion-proof buildings.

Trivia

 * Netherrack can be destroyed by hand in 2 seconds, making it the stone which can be destroyed in the least amount of time.
 * The name "Netherrack" is NOT a misspelling of "Netherrock".
 * Even though it can be set on fire indefinitely, Netherrack cannot be used as fuel in a Powered Minecart or Furnace.
 * Netherrack can be mined in 50 milliseconds with a golden Pickaxe (or a diamond pickaxe enchanted with any level of efficiency). However, there is a .25 second delay between mining blocks.
 * In the game code, it is referenced as "hellrock".