Coal is an item added by vanilla Minecraft. Coal is gained through mining Coal Ores, it is very common compared to other ores, it's primary use is for smelting in furnace or Frying Pan.
Coal is used in a the alternative torch recipes by using Natura sticks instead of vanilla Minecraft stick. There is also a Stone Rod variant added by Tinkers' Construct for torches. It is also used in the crafting of the Fire Medallion.