Conduction is the transfer of heat through direct contact between materials, from molecule to molecule. In cooking, it is the heat travelling from a hot pan into food touching it, searing a steak, or from oven walls into a roasting tray. Metals conduct well, which is why copper and aluminium pans heat evenly, while wood and plastic conduct poorly and suit handles. In physiology the term also covers the passage of nerve impulses. Understanding conduction helps cooks choose equipment and techniques: a heavy pan holds conducted heat steadily, and preheating ensures the food meets an already-hot surface for proper searing.