On laptops, If you have one, you will know. This circular plug in will be on one of the sides of the laptop. If it doesn’t have these circular plug-ins, look for an empty USB plug. USB plug-in microphones are becoming popular, as more and more people convert to using more and more mobile devices. Don’t get confused, if your laptop has two circular plug-in locations. Most laptops have two, one of them being for use with external headphones. On a desktop computer, the jack would be somewhere on a panel of the computer system (not the monitor). Again, this may be near where a USB or headphones jack would be. The microphone jack looks pretty much identical to the headphones jack. Don’t get confused, though: they are two completely different things. The headphones jack transports sound out of your computer into the headphones. The microphone jack transports sound from the microphone into the computer.