Bell-bottoms (or flares) are a style of trousers that become wider from the knees downward, forming a bell-like shape of the trouser leg.

In the 1960's, bell-bottoms became fashionable for both men and women in Europe and North America. Often made of denim, they flared out from the bottom of the calf, and had slightly curved hems and a circumference of 18 inches (46 cm) at the bottom of each leg opening. They were usually worn with Cuban-heeled shoes, clogs, or Chelsea boots.

Elephant bells, popular in the mid-to-late 1970's, were typically made of denim. Elephant bells had a marked flare below the knee, often covering the wearer's shoes. The preferred shoes were platform shoes with soles at least 2 inches (5.1 cm) thick and heels 4 to 5 inches (10 to 13 cm) to keep the pants' hems off the ground.

After the rise of punk rock in the late 1970's, bell-bottoms began to become less-fashionable as the decade drew to a close. By 1979, skin-tight trousers were much more in vogue, with bell-bottoms been seen as having had their day, remaining in fashion circa 1968-78. Today, original bell-bottoms from the 1960's and 70's are collectible vintage clothing.

More Info: en.m.wikipedia.org