A pencil skirt is a slim-fitting skirt with a straight, narrow cut. Generally the hem falls to, or is just below, the knee and is tailored for a close fit. It is named for its shape: long and slim like a pencil.

Narrow-fitting skirts have a long history in western fashion. The predecessor to the pencil skirt is the hobble skirt, a pre–World War I fad inspired by the Ballets Russes. This full-length skirt with a narrow hem seriously impeded walking.

The French designer Christian Dior introduced the classic modern pencil skirt in his 1954 Autumn Winter collection.

Along with the miniskirt, the pencil skirt quickly became very popular, particularly for office wear. This success was due to women's desire for new fashions in the wake of Second World War and Cold War rationing, coupled with the austere economic climate, when fabrics were expensive.

More Info: en.wikipedia.org