Flip-flops are a common type of footwear. They are a thin rubber sole with two straps running in a Y shape from the sides of the foot to the gap between the big toe and its neighbour. The popular use of flip-flops as beach or outdoor wear has spread through much of the world, although it is most common in India and Pakistan (where it is immensely popular and is called a Hawaii chappal), Australia, New Zealand, South Africa, UK, USA, Brazil, Panama, the Pacific Islands, and Southeast Asia.

In most developing countries, rubber flip-flops are the cheapest footwear available, often costing less than a dollar. Measures have been made to reduce cost, such as making them out of recycled tires. Because of their low cost they are very widely used in these countries as typical footwear instead of as fashion wear. Despite theirdisposable design, street vendors will repair worn sandals for a small fee.

However, in many developed countries flip-flops are typically treated as annual or seasonal, short lasting footwear. Depending on the material makeup of the shoe, some pairs of flip-flops last a year or less. The strap between the toes can snap after moderate use, and although this problem can be solved by using replacement straps that are easily "snapped" into the flip-flop, most people in developed countries do not bother to repair flip-flops because they are very inexpensive and easily replaced.

These disposal habits may pose an environmental problem because most flip-flops are made with polyurethane, which comes from crude oil. This material is a number seven resin and cannot usually be recycled in small amounts. Because of growing environmental concerns, some companies have begun to sell flip-flops made from recycled inner tubes or car tires, as well as sustainable materials like hemp, cotton and coconut.

Flip-flops are alsopopular with those who enjoy being barefoot but need to wear shoes, because they allow the foot to be out in the open but still constitute a shoe for wear in places such as restaurants or on city streets, and can be quickly and easily removed. They are also popular because they are easy to carry and come in an assortment of colors and patterns.

On July 19, 2005, some members of Northwestern University's national champion women's lacrosse team were criticized for wearing "flip-flops" to the White House to meet with President George W. Bush. The women pointed out that their shoes were not "beach shoes," but were dressier thong sandals.