What are 3.5mm jack leads used for?

This Maplin Pro 3.5mm Aux Stereo 3-Pole Jack Plug to Twin RCA Phono Braided Cable carries Stereo sound across a variety of audio devices. It is a highly versatile cable and commonly used when connecting audio equipment to smartphones and MP3 players, tablets, computers, TVs and gaming consoles. It is also used in many in-car audio and DJ audio systems.

What is Twin Phono used for?

Twin Phono is also known as an RCA connection and carries two mono signals across each Phono connector, which are combined in audio equipment for stereo sound.