Non-metallic sheathed cable, often referred to as NM cable, is a type of electrical wiring commonly used in residential buildings. It consists of two or more insulated conductors, typically made of copper or aluminum, surrounded by a non-metallic outer sheath. This sheath provides protection against moisture and physical damage, making it suitable for indoor use. The most common form of non-metallic sheathed cable is Romex, which is widely used for general wiring applications. NM cable is lightweight, flexible, and easy to install, making it a popular choice for electricians. It is designed for dry locations and is not suitable for outdoor or underground installations.