A floor plan is a drawing to scale, showing a view from above, of the relationships between rooms, spaces and other physical features at one level of a house or other structure. Dimensions (measurements) are usually drawn between the walls to specify room sizes and wall lengths. Floor plans usually include details of plumbing fixtures like sinks, or loose items such as furniture and are usually drawn to 1:100 scale.
In more technical terms, a floor plan is actually a horizontal cross section at a typical height above the floor surface so that windows and door openings are also visible on the plan. An ‘elevation’ is a measured plane projected from the side of a building, along its height, and a section or ‘cross section’ is where a building is cut along a vertical axis to reveal the interior structure.