Furnace

"The main point of a furnace is to smelt things. Smelting requires fuel - usually coal or charcoal, and an object to be smelted. Pop those in the furnace and you'll see a progress bar for the smelting process which, when completed, yields a new object. Be careful which fuel you choose, because some are more efficient than others."

- Duncan Geere

A furnace is a block used to smelt blocks and items, converting them into other blocks or items.

Obtaining
Furnaces can be mined using any pickaxe. If mined without a pickaxe, it drops nothing. A furnace also drops when a minecart with furnace is broken.

Natural generation
Two furnaces can be found inside each plains and desert village weaponsmith, and one can be found inside each igloo.

Furnaces also generate in one of savanna weaponsmith houses, inside some houses in snowy tundra villages, in one of taiga and snowy taiga village medium houses.

Crafting
The lit furnace can only be obtained in Java Edition with commands like, although it does not appear lit in the inventory. In Bedrock Edition, the lit furnace block can only be obtained by inventory editing. It always stays lit, despite containing no items.

Usage
Furnaces cannot be pushed by pistons.

Smelting
The main purpose of furnaces is to allow for smelting. Its interface can be opened by pressing the button on it.

Light source
Furnaces emit a light level of 13 when active, as well as smoke and flame particles.

Custom name
By default, the GUI of a furnace is labeled "Furnace", but this name can be customized by naming it in an anvil before placing it, or by changing the  tag using the  command.

Lock
In Java Edition, a furnace can be "locked" by setting its  tag using the  command. If a furnace's  tag is not blank, the furnace cannot be opened unless the player is holding an item with the same name as the   tag's text. For example, to lock a furnace at (0,64,0) so that the furnace cannot be opened unless the player is holding an item named "Furnace Key", use.

Block data
In Bedrock Edition, furnaces use the following data values:

Block entity
A furnace has a block entity associated with it that holds additional data about the block.

Trivia

 * Furnaces function as multiple real-world devices combined into one block: bloomeries and blast furnaces (for smelting ores), ovens (for baking and cooking), charcoal pits (for the charring of wood) and kilns (for baking of clay).
 * Tamed cats often sit on top of lit furnaces.