A Minecraft furnace is a block used to smelt ores, cook food, and burn fuel. To light a furnace, you will need to have fuel and an item that can be smelted or cooked. The fuel will provide the heat needed to light the furnace and the item will be placed in the furnace to be smelted or cooked. You can use many different types of fuel including wood, coal, and lava. Different types of fuel will last for different amounts of time. Wood will burn for the shortest amount of time, followed by coal, and then lava. You can also use a bucket of lava to fill the furnace with lava, which will provide the most fuel.
Once you have your fuel and item, you can follow these steps to light a furnace: