"Seasoned hardwood logs or chunks, because they have the most potential to release flavorful smoke. In general, alder, apple, cherry, maple, oak, and pecan produce mild-tasting smoke, while hickory, mesquite, and walnut produce stronger-tasting smoke.
After seasoned hardwood, charcoal is the next best fuel. Charcoal is wood burned in the absence of oxygen, a process called pyrolysis, in which most of the wood’s organic materials are removed, leaving behind primarily carbon, known as char.
When pyrolyzed hardwood is broken into small chunks, it is called “lump charcoal.” This lightweight form of charcoal burns quickly, so it’s generally not preferred for slow barbecuing. Charcoal briquettes, on the other hand, are made with compressed sawdust, mineral char from coal, and limestone bound together with starch; the mineral char prolongs the burn. When you need more than 45 minutes of steady heat for barbecuing, charcoal briquettes tend to provide a more consistent temperature than lump charcoal."