To connect an XLR mic to your computer, you need an audio interface. Audio interfaces are devices that fill two vital roles in the recording process: preamps to amplify the level of the mic, and digital converters to convert the analog signal from the mic into a digital signal that can be processed by your computer. Many audio interfaces have multiple inputs, allowing you to capture independent signals from multiple XLR mics simultaneously.

A mixer is designed to bring together audio from different input channels, where you can adjust the volume, apply EQ, add different effects, and then send the desired mix to one or more output channels, such as speakers or your computer. Some mixers do include an audio interface and some do not. Make sure you're looking at the correct product for your individual needs.