Your audio interface lets you get audio signals into your the music production software on your computer. It also lets you get audio signals out of your computer so that you can hear them.
There is a variety of different audio interfaces available, with varying levels of functionality, and varying levels of pricing.
The first one we are going to recommend here is claimed to be the most popular audio interface in the world, and it just happens to be the one we use most of the time.
Focusrite Scarlett 2i2
The Focusrite Scarlett 2i2 is a great audio interface that does most of what you will need for music production. Check it out on Amazon.
It has two inputs, both of which can accept microphones and instruments. This means you can record input from two sources at the same time.
The interface can handle the signals coming in from microphones, the pickups on electric guitars and basses, and electronic instruments like synthesizers.
The interface is equipped with microphone pre-amplifiers to boost the low-level signals produced by microphones, and it can supply phantom power for condenser microphones.
There are outputs on the back of the unit to send the output to an amplifier, and a headphone socket on the front for monitoring. The sound it produces is really high quality.
The version we have is the first generation Scarlett 2i2, which is great, and the second generation unit looks even better.
In addition to improvements in the processing of audio signals, the unit now comes with Ableton Live Lite and Pro Tools | First.
You can get Pro Tools | First for free from the Avid website without buying a Scarlett 2i2, but when you get it with the 2i2 (or other Focusrite interface) you also get the Focusrite Pro Tools | First Creative Pack, which includes some great software plugins to use with Pro Tools.