A barbecue spice mixture is a combination of spices and herbs used to season grilled or smoked meats. The most common RUB used for this type of seasoning is the three-letter word 'RUB'. Rubs are typically made up of a blend of herbs, spices, and other ingredients such as sugar, salt, and garlic. The ingredients are usually mixed together and then rubbed onto the meat before cooking. Rubs can be used to add flavor to any type of meat, but they are especially popular with pork, beef, and chicken.