What is carpet area, super built up area, plinth area and common areas?

Carpet area means the inside useable area between wall to wall.

Super built up area means outer wall to outer wall. This is saleable and is generally applicable to apartments. This includes the wall thickness, projected common areas and the set back area.

Plinth area means the area measured externally with respect to the whole building. Plinth area is said to include the proportionate common areas on the floor like passage, stair case, etc.

Common areas:  It is actually the covered area of the common spaces and areas meant for use by all the occupants of the building. These areas may include staircase, lifts, ducts for sanitation, electrical and air conditioning areas etc.