THHN stands for Thermoplastic High Heat-resistant Nylon-coated wire. It is a type of electrical wire commonly used in residential, commercial, and industrial applications. THHN wire is known for its durability and resistance to heat, moisture, and chemicals, making it suitable for various environments. This wire is typically made of copper or aluminum and is insulated with a nylon coating. THHN is often used for building wiring, machine tools, and other electrical installations. Its versatility and reliability make it a popular choice among electricians and contractors.