Air
Air is an invisible block used to define unoccupied space where other blocks and items could exist; it represents the absence of a block or an item. It is one of the few blocks in the game that players cannot normally interact with. Cave air is a variant found only underground in carver caves and some generated structures along with features like lava lakes. Void air is a variant used internally for the 'air' in unloaded chunks and outside of the world height limits (above Y=319 and below Y=-64 in the Overworld, and above Y=255 and below Y=0 in the Nether and the End dimensions).
Local game data
Cave Air
Air is an invisible block used to define unoccupied space where other blocks and items could exist; it represents the absence of a block or an item. It is one of the few blocks in the game that players cannot normally interact with. Cave air is a variant found only underground in carver caves and some generated structures along with features like lava lakes. Void air is a variant used internally for the 'air' in unloaded chunks and outside of the world height limits (above Y=319 and below Y=-64 in the Overworld, and above Y=255 and below Y=0 in the Nether and the End dimensions).
Appearance
All types of air are completely invisible. The only exception is that air can be visualized with the use of structure blocks in Save mode: when "Show invisible blocks" is enabled, air is represented as small blue-edged cubes. Air, cave air, and void air are all displayed identically.
Natural generation
Upon world generation, all otherwise empty spaces are occupied by air. , carver caves and some underground structures generate containing cave air instead, including mineshafts, strongholds, monster rooms, and lava lakes, and void air is used in place of unloaded chunks and above or below the world's buildable area to denote illegal locations for blocks to be put.
Post-generation
When other blocks are destroyed by any means, air is created.
Usage
Air shares some properties with non-solid blocks, including allowing the player or mob to move within that space without suffocating, and also to catch their breath if they are drowning in water. Cave air and void air have no special properties; they function the same as normal air.
Piston interactivity
Air and its variants are destroyed when pushed by a piston. They cannot be pulled by sticky pistons.
Trivia
, in the arguments for , cave and void air are treated as regular air, meaning that also fills cave air and void air. When trying to replace cave or void air, the command fails even if cave or void air is present.