Audio output – Audio output (port) used for e.g. headphones, speakers and other similar devices.
Microphone input – Audio input for e.g. a desktop microphone or similar devices.
Combined audio connector – This type of connector combines audio input and audio output in one connector of the same size. A combined audio port cannot be used to connect a separate microphone; the microphone must have a combined audio jack to work. However, separate headphones/speakers will work when plugged into this port without issue.