Block entity

Tile entities are additional data for a block, beyond the block ID and 4 bits of “metadata” that every block has (as described in the data values article).

The blocks which have tile entities are:
 * Signs, to store the text on them.
 * Chests, Dispensers, and Furnaces, to store their contents. Furnaces also store the time until the current item is smelted, and the time until they will need another fuel item.
 * Monster Spawners, to store what mob they will spawn that will spawn and the time before the next mob is spawned.
 * Note Blocks, to store the note played.
 * Blocks being moved by the upcoming pistons, to store the offset of block, direction of movement, and ID of moving block.