Originally in medieval England the common was an integral part of the manor, and was thus part of the estate held by the lord of the manor under a feudal grant from the Crown or a superior peer, who in turn held his land from the Crown which owned all land.
This manorial system, founded on feudalism, granted rights of land use to different classes. These would be appurtenant rights, that is the ownership of rights belonged to tenancies of particular plots of land held within a manor. A commoner would be the person who, for the time being, was the occupier of a particular plot of land. Some rights of common were said to be in gross, that is, they were unconnected with tenure of land. This was more usual in regions where commons are more extensive, such as in the high ground of Northern England or on the Fens, but also included many village greens across England and Wales. More about common land on WIkipedia.