Netherrack

"Netherrack was added to the Java edition of Minecraft in Alpha version 1.2.0, the Halloween Update, alongside pumpkins, clocks, fishing and the Nether. Spoiler alert: the Nether is where netherrack gets its name from (though it was originally called “bloodstone”, eww), and it’s also where you’ll find more netherrack than any one person could ever need."

- Duncan Geere

Netherrack is a rock-like block found in the Nether.

Obtaining
Netherrack can only be collected with a pickaxe.

Natural generation
Netherrack makes up most of the Nether's terrain.

Netherrack generates as part of nether portals spawned floating.

Netherrack regenerates when the player resets the Nether.

Endermen
Endermen can pick up netherrack, and will drop the block they are holding if killed.

Usage
When netherrack's top is lit on fire, the fire will burn indefinitely.