A method of describing the boundaries of a parcel of land, also commonly referred to as a legal description.
A metes and bounds description defines a parcel of land by specifying an origin point and then a series of boundry line descriptions (often known as calls) that traverse the edges of the parcel. Most often give as a bearing and a distance in modern descriptions, at its simplest a call could be '50 paces northerly to a large oak tree'.
Modern usage in the United States is strongly related to the Public Land Survey System (PLSS). A metes and bounds is often called a legal description, though it is but one possible type of legal description. See the Wikipedia entry for more detailed information.