The type first introduced are called mini-plug and have one or two small round segmented pins that are plugged into the audio ports of the computer.
The second type, USB (Universal Serial Bus), were developed and standardized later on (around 1996) but were not in wide use on computers until 1999 - 2000.
USB connectors consist of a single rectangular plug as shown in the table below.
The mini-plug type of devices are usually plugged into the ports found on the sound card on the back of the computer and some manufacturers also include mini-plug ports on the front of the computer for easier access.
USB ports can also be found on the front or back of most PC's manufactured since the late 1990's.
The table below shows examples of the connectors and ports, as well as some of the icons used to identify them.
| USB | Mini-plug | |
|---|---|---|
| Device Plug/Connector |  |
 |
| Computer Port(s) |  |
 |
| Comments | USB
ports may or may not have the '2.0' designation next to the USB icon
as shown above. The standard USB icon looks like  |
Typically
the microphone input is pink or red while the headphone input is
green. Mini-plug connectors and ports also usually have icons on or near them for identification as well as the pink and green color coding. Another common Microphone icon is  Common Headphone icons look like 
with  on
the computer port. DO NOT plug either headset connector into the blue port or the one marked  |