A bed sheet is a piece of cloth that is designed and used to cover a mattress. A bed sheet serves the purpose of keeping the mattress clean from dirt and provides a more comfortable feel to the sleeper than if he or she were to simply lay on top of the mattress with no sheet.
In some parts of the world, a second bed sheet is placed on top of the sheet that covers the mattress. This second sheet is referred to as a “top sheet.” When this top sheet is put in use, the sheet directly on the mattress is referred to as a “bottom sheet.” A sleeper lies between the two sheets. Blankets, comforters, and any additional bed covers are put above the second bed sheet.
Bed sheets are available in two types: flat and fitted. A flat bed sheet is nothing more than a rectangular-shaped piece of linen. A fitted bed sheet features four corners with elastic bands around the edges and is used as a bottom sheet. A reason for using a fitted bottom sheet is to prevent it from slipping off of the mattress while the sleeper moves around on the bed. A unique method of folding and tucking while making up a bed is referred to as “hospital corners,” and this is typically employed when the bottom sheet is flat as opposed to fitted.
Bed sheets have historically been white, but in modern times many different colors and patterns are available. The quality of bed sheets is often conveyed by the thread count. The thread count is the number of threads per square inch of bed sheet material. Usually, the higher the thread count, the softer the sheet is. Common materials used in making sheets are cotton, linen, blends of cotton / polyester, silk, wool, rayon, and others.