Linen is a textile made from the fibers of the flax plant, Linum usitatissimum. Linen is labor-intensive to manufacture, but when it is made into garments, it is valued for its exceptional coolness and freshness in hot weather.

Textiles in a linen-weave texture, even when made of cotton, hemp and other non-flax fibers are also loosely referred to as "linen". Such fabrics generally have their own specific names other than linen; for example, fine cotton yarn in a linen-style weave is called Madapolam.

The collective term "linens" is still often used generically to describe a class of woven and even knitted bed, bath, table and kitchen textiles. The name linens is retained because traditionally, linen was used for many of these items. In the past, the word "linens" was also used to mean lightweight undergarments such as shirts, chemises, waistshirts, lingerie (a word which is cognate with linen), and detachable shirt collars and cuffs, which were historically made almost exclusively out of linen.

Linen textiles appear to be some of the oldest in the world: their history goes back many thousands of years. Fragments of straw, seeds, fibers, yarns, and various types of fabrics which date back to about 8000 BC have been found in Swiss lake dwellings. Dyed flax fibers found in a prehistoric cave in the Republic of Georgia suggest the use of woven linen fabrics from wild flax may date back even earlier to 36,000 BP.

Linen was sometimes used as currency in ancient Egypt. Egyptian mummies were wrapped in linen because it was seen as a symbol of light and purity, and as a display of wealth. Some of these fabrics, woven from hand spun yarns, were very fine for their day, but are coarse compared to modern linen.

Today linen is usually an expensive textile, and is produced in relatively small quantities. It has a long "staple" (individual fiber length) relative to cotton and other natural fibers.

Many products are made of linen: apron, bags, towels (swimmers, bath, beach, body and wash towel), napkins, bed linen, linen tablecloth, runners, chair cover, man and woman wear.