The BNC connector (Bayonet Neill Concelman) is a miniature quick connect/disconnect RF connector used for coaxial cable. 

It features two bayonet lugs on the female connector; Mating is achieved with only a quarter turn of the coupling nut. BNCs are ideally suited for cable termination for miniature-to-subminiature coaxial cable (e. G., RG-58, 59, to RG-179, RG-316). 

It is used with radio, television, and other radio-frequency electronic equipment, test instruments, video signals, and was once a popular computer network connector. BNC connectors are made to match the characteristic impedance of cable at either 50 ohms or 75 ohms. 

The BNC connector is used for signal connections such as: 
Analog and serial digital interface video signals 
Amateur radio antennas 
Aerospace electronics (avionics) 
Test equipment.