Block entity

Tile entity is additional data about block, beyond the block ID and 4 bits of metadata that every block has (as described in the data values article).

The blocks which are tile entities are:
 * Signs, to store the text on them.
 * Chests, Dispensers, and Furnaces, to store their contents. Furnace also stores time until item is cooked/smelt, and time until it will need new fuel item.
 * Mob spawners, to store mob that will spawn and time before next mob is spawned.
 * Note Blocks, to store note.
 * Blocks, moved by upcoming pistons, to store the offset of block, direction of movement, and ID of moving block.