That's the bad news. The good news is that it's inexpensive and, when properly finished, yields a first-rate interior surface.
Drywall comes in a variety of sizes and thicknesses.
Regardless of length or thickness, most panels are constructed in the same way. The ends are full thickness, but the long sides are tapered toward the edge of the panel. When two panels are abutted, edge to edge, a depression is created to accommodate the compound that's needed to finish the joints later. So it's best to avoid butt joints whenever possible, even if you have to waste some material. For this story, we installed drywall in a typical two-story house, which gave us the chance to try out a number of techniques before settling on the ones shown here.