Barbecue, also spelled barbeque, or BBQ is a method of cooking meat with the heat and hot gasses of a fire, the application of a vinegar-based sauce to meat, the end-result of cooking by this method, or a party that includes such food. Barbecue is usually cooked in an outdoor environment heated by the smoke of wood, or charcoal. Restaurant barbecue may be cooked in large brick or metal ovens specially designed for that purpose.
Barbecue has numerous regional variations in many parts of the world. Notably, in the South and Midwest of the U.S., practitioners consider barbecue to include only relatively indirect methods of cooking, with the more direct high-heat methods to be called grilling.
For those that distinguish the terms, grilling is almost always a fast process over high heat and barbecue is almost always a slow process using indirect heat and/or hot smoke.
The slower methods of cooking break down the collagen in meat and tenderizes tougher cuts for easier eating. (adapted from Wikipedia)