Stones (st) are a unit of weight or mass commonly used in the British imperial system, primarily in the United Kingdom and Ireland. The stone is not commonly used in the United States customary system or in many other parts of the world.

One stone is equivalent to 14 pounds (1 st = 14 lb). The stone is often used as a convenient unit for measuring body weight, especially for personal weight management and discussing body weight in everyday conversations in the UK.

The stone is primarily used to measure human body weight in the British context. People often express their weight in stones and pounds. For example, someone may say their weight is "12 stone 6 pounds," which means they weigh 12 stones and 6 pounds, or approximately 174 pounds (since 1 stone = 14 pounds).

It's worth noting that stones are not commonly used for measuring the weight of objects or commodities outside of the UK and Ireland. In other countries, pounds or kilograms are the preferred units for measuring weight.