Air

Air is the absence of a block. It was created in Minecraft very early. Air blocks are entirely transparent and can only be destroyed or created by placing or destroying other blocks. Air and Non Solid Blocks are the only space the player and other Mobs are allowed to move; in Alpha mode, entering a block will suffocate whatever is inside. Air will restore all bubbles on the Air meter and make it disappear.

In the current Creative and Survival Test modes, Water is infinite and will fill any air that is horizontal to it or below it. In Indev, if a pool of water comes in contact with air horizontally, there is a 2/3 chance the water will recede and turn to another air block. There is a 1/3 chance the water will advance and turn the air to water.

Due to air's ability to be located on the map anywhere, it must be treated as a block by map editing software.