The three main categories of pigtail connectors are RF/coaxial pigtails, fiber optic pigtails, and electrical/automotive pigtails. The term pigtail refers to the physical appearance of the wire, which often resembles the curly tail of a pig before it is installed. Technically, it is a cable assembly that provides a connection interface. It's a short wire with a connector installed on one end, such as a spade or ring terminal, while the other is left bare or blank.