Peat is an accumulation of partially decayed plants. Partial decay (humification) occurs under conditions of restricted microbial activity.
Although some higher plants, such as sedges or reed, are also capable of producing certain amounts of peat, peat moss is the classical producer of high-quality peat.
Peat is an early stage in the transformation of vegetation into coal and is used as a fuel. Ireland obtains more than 20% of its energy from peat.