Balanced connections are extremely important in audio recording and production because they allow for the use of very long cables without the introduction of outside noise. The most common balanced connection is
XLR, which is used with microphones because of its durable construction. Microphones also have very low
impedance (Z), which makes long microphone cables susceptible to outside noise, and a perfect application for a balanced circuit, which cancels out this outside noise.
A balanced connection has three wires, and works by using one wire that is in phase, the other out of phase, and the third is a ground. The idea is that on long signal runs noise induced on the cable is rejected through phase cancellation at the audio input.
While XLR connections are the most common balanced connector, 1/4" TRS (Tip Ring Sleeve) connectors are also commonly used.