Drywall is made up of large sheets of plasterboard, usually screwed to interior stud work or ceiling joists to form a smooth surface for finishing. It is also used to finish solid walls where it is either bonded directly to the wall or screwed to battens fixed to the wall.
Boards come in two main varieties - square edged and tapered. Tapered boards have a slightly thinner edge which takes the tape used to cover the joins.
Tapered edge boards are ideal for either jointing or skimming, while square edge is generally used for textured finishes.
Drywall can also come with insulation and soundproofing layers attached. This is usually thicker and heavier boards.