Tights are a kind of cloth leg garment, most often sheathing the body from above the waist to the feet with a tight fit, hence the name. Wearing of tights has a history going back several centuries, when they were worn by men. Today, they are worn primarily by women and girls and some men and boys, as well as infants and toddlers of both sexes. In recent years, they have been sometimes offered as men's fashion. Athletic tights are already considered unisex.
In American English, the difference between pantyhose and tights is determined in the weight of the yarn used and the thickness to which the garment is knitted. Generally, anything up to 40 denier is known as pantyhose and anything over can be classified as tights, as for example 'running tights' and 'cycling tights'. In the United Kingdom, the word "tights" is used in all cases when referring to pantyhose, and "leggings" for hosiery of heavier, normally opaque material. Tights can be sheer yet solid in colour, whereas leggings are opaque, not sheer.