What is peat?
Peat is a heterogeneous mixture of more or less decomposed plant (humus) material that has accumulated in a water-saturated environment and in the absence of oxygen.
Its structure ranges from more or less decomposed plant remains to a fine amorphic, colloidal mass. The warmer the climate, the quicker the plant material will decompose. The rate of accumulating plant material is greatest in areas where the temperature is high enough for plant growth but too low for the vigorous microbial activity that breaks down the plant material. Such conditions are found more frequently in the northern hemisphere.
In "Wise Use of Mires and Peatlands" by Donal Clarke and Hans Joosten (2002), the following terms are used:
A wetland is an area that is inundated or saturated by water at a frequency and for a duration sufficient to support a prevalence of vegetation typically adapted for life in saturated soil conditions.
Peat is sedentarily accumulated material consisting of at least 30% (dry mass) of dead organic material.
A peatland is an area with or without vegetation with a naturally accumulated peat layer at the surface.
A mire is a peatland where peat is currently being formed.
A suo is a wetland with or without a peat layer dominated by a vegetation that may produce peat.