Smoking is a cooking and preservation technique that exposes food to smoke from burning wood or other aromatic materials, which flavors the food and, historically, helped dry it out and inhibit microbial growth before refrigeration was available. It falls into two main types: cold smoking, done below about 100°F (38°C) for hours or days, used mainly to flavor and preserve meat, fish, and cheese without cooking it; and hot smoking, done at roughly 150-225°F (66-107°C) for a shorter time, which both cooks and flavors the food. The wood used, along with temperature and time, shapes the result: hickory, oak, and mesquite give bold, earthy flavors, while apple and maple give a sweeter, milder smoke. Smoked salmon, meats, and cheeses are common results, used in appetizers, salads, barbecue, chili, stews, sandwiches, and casseroles.