A skirt is a tube- or cone-shaped garment that hangs from the waist and covers all or part of the legs.

In European culture, skirts are usually considered women's clothing. However, there are exceptions. The kilt is a traditional men's garment in Scotland, and some fashion designers, such as Jean-Paul Gaultier, have shown men's skirts.

At its simplest, a skirt can be a draped garment made out of a single piece of material (such as pareos), but most skirts are fitted to the body at the waist and fuller below, with the fullness introduced by means of dart, gores, pleats, or panels. Modern skirts are usually made of light to mid-weight fabrics, such as denim, jersey, worsted, or poplin. Skirts of thin or clingy fabrics are often worn with slips to make the material of the skirt drape better and for modesty.

The hemline of skirts can be as high as the upper thigh or as low as the ground, depending on the whims of fashion and the modesty or personal taste of the wearer.

Some medieval upper-class women wore skirts over three metres in diameter at the bottom. At the other extreme, the miniskirts of the 1960s were minimal garments that may have barely covered the underwear when seated.

Costume historians typically use the word "petticoat" to describe skirt-like garments of the 18th century or earlier.