Drywall is a construction product commonly used to finish building interiors. For hundreds of years prior to its development, the interior walls of buildings were usually made of plaster. This was applied in layers over narrow boards called laths that were nailed directly to the studs. The plaster was pressed into gaps between the laths to make it adhere, and was built up in progressive layers. This building technique called for a fair degree of craftsmanship and experience, but allowed the builder to incorporate interesting textures or decorations as the plaster was worked.
In the mid-twentieth century, drywall, also called plasterboard, sheetrock or gypsum board, came into widespread use, and now almost all buildings have drywall walls. Drywall has a number of advantages over plaster, ease of installation being the most obvious. Any reasonably handy person can refinish a room with drywall, and you don't have to take any training or join a guild to learn how to do it.
Drywall is made using gypsum plaster, which is then covered on both sides by fiberglass matting or heavyweight paper. Depending on the manufacturer, certain additions, such as anti-mildew and fire-resistant materials, are mixed with the gypsum plaster before applying the paper.
Finishing an unfinished basement room with drywall, for instance, can be the work of a weekend. The drywall, which comes in sheets that are designed for modern house codes, can simply be nailed to the standing studs. Cutting holes for outlets, wall switches and light fixtures can be easily done with a keyhole saw - make your measurements carefully.
Once the drywall is up, the joins between sheets are covered with a special tape, and the tape and the nails are covered with a spackle-like paste called joint compound. The joint compound must be allowed to fully dry on the drywall, after which you can sand it to smoothness. If done properly, the tape and joint compound process will hide the seams between sheets of drywall.
A common household blemish is the popped nail. This often appears in the ceiling, where a nail holding the drywall in place has popped out, or perhaps the joint compound has flaked off and left the nail visible. This is easy to fix; if the nail has popped out altogether, reposition it an inch or so away and nail it back in again, then hide it with joint compound and sand or paint, as in a new drywall installation. Older homes might have a number of these little nail glitches throughout, but a few minutes on a ladder can have your drywall ceiling looking spotless and seamless again.