Definition: A sheet set includes a fitted sheet, flat sheet and pillowcases. All sets include two pillowcases with the exception of the Twin Set which includes just one pillowcase.
Be sure to note the pocket size when purchasing sheet sets. Pocket size refers to the depth of the mattress your sheet can accommodate. Most standard mattresses are 12" deep, most deep-sized mattresses are 15" and extra-deep mattresses are 18".