A sweater is a garment created to protect the body of a person or animal from the cold and to keep in body heat. Sweaters are usually made of wool, but also can be made of cotton or of man made materials. Some sweaters are designed to be heavy and provide warmth while keeping the wearer dry in harsh, damp elements, while other sweater designs are lighter and worn in cool weather in friendlier climates.

Sweaters can be designed with buttons or zippers for easy wearing. Some sweaters are commonly found and purchased in department stores or through catalogs, while other sweaters are designed with distinct cultural histories depicted in the weave and represent different types of lifestyles from all over the world and may be ordered through specialty stores or web sites.

There are sweaters made for infants, older children, men and women as well as pets. Designers of sweaters manufacture their sweaters with knitting needles or crochet hooks, on looms or with machines, using varying material ranging from wool to cotton to synthetic man made fibers and combinations of organic and non natural fibers. There are argyle sweaters, cardigan sweaters, cashmere sweaters and cultural specific sweaters such as Aran sweaters and Nordic sweaters.