In the case of USB microphones, the audio interface is built into the microphone itself.
- Physically connect the microphone to the computer via USB.
- Ensure the proper drivers are downloaded/installed (a one-time event).
- Select the interface (USB microphone) to be the audio input of the computer and/or software.
- Adjust the microphone gain to a reasonable level.
A USB mic acts as both a microphone and an audio interface. Many USB microphones even come with a zero-latency headphone output, effectively functioning as a true input/output interface device!
The main benefit of USB microphones is they are easy to use. The setup could be as simple as one USB mic, one USB cable, and one computer. Simply connect the microphone, download the drivers, and it works!
Of course, there are downsides to USB microphones, too.
The interface of a USB mic will only allow one microphone-to-computer connection at a time. USB microphones also, generally speaking, have worse specs (quality) than professional XLR microphones (though this isn’t always the case).
USB microphones are terrific for monologue recording or any other recording of a single source. They are also a significant upgrade over built-in or “mini-plug” computer microphones!
For an in-depth read about microphone specifications (of analog and digital mics), please consider reading my articles.