This FAQ is all about mixer outputs. If you want to know about inputs (ie for Mics, Guitars, Keyboards) this FAQ is not for you.

 mixer outputs

The output connections is where you connect your mixer to various components like amps, powered speakers or recording devices. The outputs on a mixer come in 3 types:

XLR & TRS  Balanced  +4dBu  1.2V
RCA & TS Unbalanced  -10dBv 0.3V
Headphones Unbalanced Amplified   

A Balanced cable will generally have 3 conductors (2 signal and one ground). One signal is reversed in polarity. With the correct gear, the cable noise can then be cancelled out.

Generally the XLR outputs will sound louder than the RCA.

For distances greater than 10m - use the Balanced XLR outputs to reduce noise.

TS: Tip and Sleeve (mono plug)

TRS: Tip, Ring and Sleeve (stereo looking plug...but is generally used for balanced signal in this case)