bed sheet (also known as a "flat
bed sheet") is a type of beddingó
a large rectangular piece of cotton
or linen cloth bed cover. It is this
sheet that one typically lies on. They
were traditionally white, but now often
various colors and patterns are used.
They are larger than the bed, so they
can be tucked under the mattress in
order to be kept in place. The quality
of bed sheets is often conveyed by the
thread count - the number of threads
per square inch of material.
A "fitted" bed sheet is not
a simple flat cloth, but is sewn to
match the shape of the mattress. The
corners are fitted with elastic so they
can be stretched over the mattress,
and then the edges can be tucked under
the mattress. Sometimes confused with
a comforter, it is usually found under
a comforter, but over the mattress cover.