A Minecraft furnace is a block used to smelt ores, cook food, and burn fuel. It is one of the most important blocks in the game, as it allows players to obtain valuable resources and create essential items.
To use a furnace, players must first place it on the ground. They can then add fuel to the furnace by placing a coal, charcoal, or lava bucket in the bottom slot. Next, they can add the item they want to smelt or cook to the top slot. The furnace will then begin to burn the fuel and heat the item, eventually smelting or cooking it.