Placeholder texture

Minecraft uses an assortment of different placeholder textures for handling cases where textures cannot be drawn normally.

Missing texture
Perhaps the most famous of all cases, the missing texture, a texture composed of a black and magenta checkerboard, turns up anytime a texture or model reference could not be correctly resolved,

Animation placeholder textures
Another type of placeholder texture, these were overwritten by the actual animated textures during gameplay once said textures were generated by the game. Needless to say, they would appear themselves if the animation could not be generated for whatever reason.

Texture atlas blank spaces
When predefined texture atlases were used for storing and loading textures, certain patterns were used for marking unused regions on some atlases, where others simply used outright blank spaces.