Since humans first cultivated sheep, cultures have made soft sheepskin boots.Their popularity diminished once leather tanning of more durable leather products like cowhide increased. Unlike cowhide, the sheepskin is soft and easily abraded, limiting it to gentle use. Sheepskin boots gained in popularity as a result of World War I and World War II, when they were popular with aviators because of the need to maintain warmth in non-pressurized planes at high altitudes. An exhibit of a WWI aviator’s outfit in the Canadian War Museum cites the term “fug” boots. Ugg boots have also been popular with surfers and competitive swimmers since at least the 1960s, for keeping warm while out of the water.

 Uggs became ubiquitous among Southern California surfers and Southern California downhill skiers, and from there, uggs were popularized by Hollywood into the American mainstream and later the worldwide market.

Uggs have been identified as a fashion trend for both sexes since the early 2000s. Ugg boots ride the vagaries of fashion trends, with a growth in popularity for men tied to increased celebrity usage (e.g., Leonardo DiCaprio). Men and women especially of college age, teens, and tweens wear Uggs with jeans, dresses, shorts and long shirts or sweaters with leggings, footless tights, or knee socks and sometimes without any legwear.