How To Record Your Podcast Guest To Audacity

Whaa?
For when you want to capture audio for a screen-sharing session, or record audio from streaming sources–such as live web-casts–that don’t necessarily allow you to download content immediately, 
 you’d open up your audio recording application of choice (like Audacity), and find the option for microphone input.

Select Stereo Mix as your input (if it isn’t already), be sure other recording devices are muted or disabled, and click record.
Enable “Stereo Mix” in Windows and Record Audio from Your PC
Go down to the audio icon in your system tray, right-click it, and go to “Recording Devices” to open up the proper settings pane.

I get it.
In the pane, right-click on a blank area, and make sure both “View Disabled Devices” and “View Disconnected Devices” options are checked.  You should see a “Stereo Mix” option appear.
Right-click on “Stereo Mix” and click “Enable” to be able to use it.
With “Stereo Mix” enabled, you can open up your favorite recording program and select that instead of your microphone before you record.  If you don’t see the option, or your program doesn’t give you the ability to change the recording device, you can disable or unplug your microphone and make “Stereo Mix” the default recording device.