A PC’s input and output ports connect it to devices such as keyboards, monitors, headsets and networks. Many ports carry information in both directions. The connector’s shape tells you what can fit, but the computer’s manual tells you which features that particular port supports.
Common external ports
| Port | Typical use | What to check |
|---|---|---|
| USB-A or USB-C | Keyboards, storage, phones and other accessories. | Data speed, charging support and the correct cable; USB-C does not guarantee video. |
| HDMI or DisplayPort | Connect a display; commonly carries audio too. | Output versus input, supported picture mode and cable/adapter. |
| Ethernet, often called RJ-45 | A wired network connection. | Computer, cable and network equipment must support the speed you want. |
| Headphone, microphone or line-audio jack | Analogue audio input or output. | The icon, connector type and whether the port combines microphone and headphone functions. |
| S/PDIF, optical or coaxial | Digital audio to compatible equipment. | The formats the source and receiver support. |
| SD or microSD reader | Memory cards. | Card type, reader support and write-protection status where relevant. |
| Power input | Connect a compatible power supply. | Exact voltage, connector and power requirements. |
A USB storage device sends and receives data, and an Ethernet connection does too. Calling one of these a purely “input” or “output” port can therefore be misleading. A video output, in contrast, is not automatically a video-capture input.
Read the model’s port list
A manufacturer guide, such as this Dell port list, identifies the actual functions and optional features of one model. It is an example of where to check, not a specification for every PC.
Colour and shape alone are not enough. A USB-C socket may provide data without display output or charging. VESA’s DisplayPort FAQ explains video over a compatible USB-C connection.
Audio connectors need the right job and wiring
Look for microphone, headphone or line labels before plugging in. A combined headset jack can differ from separate microphone and headphone sockets. Use an adapter designed for those exact connections rather than assuming any plug of the same diameter works.
S/PDIF sends digital audio, but it does not automatically provide every surround format or better sound than every analogue setup. The devices, format and connection determine what works.
PCI Express and M.2 are internal connections
PCIe expansion slots connect devices such as graphics or network cards inside the PC. M.2 is a compact connector/form factor used for devices including storage and wireless modules. Not every M.2 slot or drive is interchangeable.
Intel‘s motherboard guide explains that M.2 devices can use different interfaces, including PCIe or SATA. Check the board manual for supported sizes, keys, interface, lane sharing and installation instructions. Do not choose a drive simply because its outline fits.
Older connectors still have uses
VGA, DVI, PS/2, serial and parallel ports can still appear on older or specialist equipment. A common 9-pin serial connector is not a parallel printer port. Avoid the earlier article’s claim that these ports have all ceased to exist.
Use a suitable adapter only after checking the protocol and direction. A passive change of plug does not translate every type of signal.
For display connections, see our video-port guide. For power, check laptop charger connectors, voltage and wattage.
Information checked October 13, 2026, using the guides linked above.