A floor plan is a drawing that shows a room as seen from above. Everything in a floor plan appears flat. Architects use floor plans to show what a room or building will look like. Anyone who draws (or drafts) a floor plan is called a draftsperson.
A floor plan is drafted in miniature scale. This means that the whole drawing of the room fits on one sheet of paper (although sometimes it is a big sheet of paper). Maps and atlases are drawn in miniature scale too. A blueprint of a room or building is a scale drawing drafted on a big piece of blue paper.
A common scale is 1/4 inch equals 1 foot. This means that if something is drawn 1/4 inch long on a piece of paper, it is 1 foot long in real life. In the drawing to the right, the back wall is 6 inches long on paper, so it is 24 feet long in real life. If something is drawn the exact same size as it is in real life, it is called "full scale." A draftsperson always indicates the scale used in a floor plan. In a street map, a scale may be 1 inch equals 1 mile.
A floor plan usually shows the actual measurements for lengths in real life. In the example to the right, the back wall is 24 feet long in real life and the side wall is 30 feet long. The name of the lines that show the lengths of walls are called dimension lines. Other dimension lines may show the length of windows, the distances from walls to windows, and so on.
Floor plans may be drafted by hand with a pencil, ruler, and graph paper. Graph paper has grid lines preprinted on the paper. This makes scale drawings easier to create, since one of the 1/4-inch lines on the paper can represent 1 foot in real life. Graph paper may have millimeter grid lines, which represent 1 meter in real life.
Floor plans may be drafted by computer, using computer-aided design (CAD) software. CAD software includes AutoCAD, MS PowerPoint, Google Slides, and many other drawing programs. CAD software makes it very easy to draft floor plans to scale.
The above picture is a floor plan, drafted to 1/4"=1' scale, with dimensions shown.