There are two main types of coaxial cables – ones with an impedance of 75 Ohm (Ω) and ones with an impedance of 50 Ohm. Cables with 75 Ohm are mostly used for video signals, while 50 Ohm cables tend to be used for data and wireless communications. When we speak of coaxial cables, the Ohm refers to impedance. This impedance is the measure of resistance in the cable to the flow of electric energy.