A patch cable or patch cord (sometimes patchcable or patchcord) is an electrical or optical cable, used to connect ("patch-in") one electronic or optical device to another for signal routing. Devices of different types (ie: a switch connected to a computer, or switch to router) are connected with patch cords. Patch cords are usually produced in many different colours so as to be easily distinguishable, and are relatively short, perhaps no longer than two metres. Types of patch cords include microphone cables, headphone extension cables, XLR connector, RCA connector and ¼" TRS connector cables (as well as modular ethernet cables), and thicker, hose-like cords (snake cable) used to carry video or amplified signals. However, patch cords typically only refer to those short ones used with patch panels.
Patch cords can be as short as 3 inches or 8 cm, to connect stacked components, or route signals through a patch bay, or as much as twenty feet or 6 m or more in length for snake cables. As length increases, cables are usually thicker, and/or made with more shielding, to prevent signal loss (attenuation) and the introduction of unwanted radio frequencies and hum (electromagnetic interference).
Patch cords are often made of coaxial cables, with a positive or "hot" signal carried through a shielded core, and the negative electrical ground or earthed return connection carried through a wire mesh surrounding the core. Each end of the cable is attached to a connector, so the cord may be plugged in. Types of connectors may vary widely, particularly with adapting cables.
Patch cords may be:
A very short patch cable may be called a pigtail. These may be used, for example, to connect a wall-mounted telephone to the wallplate. The name may also be synonymous with a dongle if it is also an adapter.