1 channel mono, balanced. Used for microphones, speakers, subwoofers, monitors, mixers, and due to its balanced nature and shielding is ideal for long distance cable runs.
1 channel mono, unbalanced. Used for musical instruments and shorter audio device connections. Splitter cables such as stereo to two mono channels may use this type of plug.
2 channels of unbalanced stereo audio or 1 channel of balanced audio. Used to connect headphones and other consumer electronics. Available in quarter-inch and eighth-inch sizes. The eighth-inch size is also called 3.5mm.
1 channel mono, balanced. Used to connect devices like CD/DVD players to mixers.