[LAU] PulseAudio - Internal Audio

Hello I am a total noob when it comes to sound in linux. I have Ubuntu and I was trying to record what I was hearing. I did it but I have a question. I installed PulseAudio Volume Control (pavucontrol) and noticed the "Configuration" tab, where it has an "Internal Audio" profile with options like: * Analog Stereo Duplex * Analog Stereo Output * Digital Stereo Duplex (iec 958) + Analog Stereo Intput * Digital Stero Duplex (iec 958) * Off I tried to find more information about these options, but there is no "help" for this GUI. SO I was wondering if anyone could give any hints (links, documentation etc) on what these settings are. Vag