Most of the connectors at the back of your computer are familiar while some are not. Here is a visual guide to all the possible plugs and sockets you’ll encounter.

Very often, people peek at the back panel of their computer or laptop and wonder what all those connectors are for. While many of them are indispensable, many others might never need to be used at all. SOme might be there only in case you ever need an older peripheral, and some duplicate each others’ functionality for no apparent reason. If you’ve ever been confused by the variety of ports out there or if you’ve never known which ones you need, this handy reference guide should give you everything you need.

1. D-sub (D-subminiature): A very common display connector for monitors/display panels.     Usually found in CRT monitors, this connector will soon be phased out on feature LCD monitors with DVI, HDMi or DisplayPort connectors.
   

   D-Sub Port

2. DVI (Digital Visual Interface):
   

   DVI Ports

   It is the  digital display output port currently used for most LCD monitors. It is superior to the D-Sub VGA standard.

3. HDMI (High-Definition Multimedia Interface): A single media output interface which incorporates high quality audio/video output in one single cable for high-definition TVs and monitors.
   

   HDMI Connectors

   The current standard is 1.3, though it keeps evolving. HDMI also supports HD anti-piracy measures.

4. DisplayPort: A digital display interface similar to HDMI, but with a higher data transfer rate.
   

   DisplayPort

   Yet to be implemented in desktop monitors, this port has already made its entry on some graphics cards. The connector is much smaller and more convenient than DVI.

5. Component Video: Comprises of three analog video signals: Y, Pb and Pr. Usually used where high quality video is required with resolution up to 1080p.
   

   Component Video

   It does not carry audio on the same cable. This type of interface is found on DVD players and TV sets, while most graphics cards need an adapter.

6. Composite Video: It is an analog video output with three signals Y, U, and V combined together with sync pulses.
   

   Composite Video

   It supports standard video resolution of up to 480i and does not carry audio on the same cable. Found on most VCD/VCRs, DVD players, TVs, camcorders and certain graphics cards. This is easily the lowest quality video interface.

7. S-Video: Also known as Super-Video, is similar to composite video output, but with two seperate video signal lines for Luminance and Chroma.
   

   S-Video

   It supports video resolutions of up to 576i and does not carry audio on the same cable. This type of interface is seen in digital camcorders, DVD players, and certain graphics cards.

8. RJ11 and RJ45 (Registered Jack-11 and 45): These are connectors for communications-related and networking purposes. RJ11 is used for telephone connections,
   

   RJ 11 & RJ 45

   while RJ45 is used in twisted pair Ethernet connections. The RJ11 connector is smaller than the RJ45 connector. The two have 6 and 8 pins respectively.

9. Coaxial S/PDIF (Sony/Philips Digital Interconnect Format): It is an interface to carry compressed digital audio data (multi-channel support) over a single wire using a standard RCA jack.
   

   SPDIF

   Similar to optical S/PDIF, which carries signals using light as a medium via an optical fiber cable.

10. Audio in-out: This is the most common audio input and output port type. It usually is a 3.5mm earphone-type plug and socket, and carries stereo audio signals for the left and right speaker channels.
    

    Audio In & Out

    Multiple audio ports can be used to carry multi-channel audio output. The audio ports on a motherboard are color coded according to their targets.

11. PS/2 (IBM Personal System/2): It is generally an input port used for keyboards and mice. The purple PS/2 connector is for the keyboard, while the mouse connects to the green PS/2 port.
    

    PS/2

    It is found on motherboards only, but is already being phased out because of the growing adoption of USB peripherals.

12. FireWire (IEEE 1394): FireWire is used for high-speed data transfers. It is found in two variants- FireWire 400 and FireWire 800. The data transfer speeds attained by FireWire 400 and FireWire 800 connections are 400 Mb/s and 3200 Mb/s respectively.
    

    FireWire

    Both are usually used for importing video from camcorders or hard drives, but are losing out to high-speed USB 2.0.

13. Parallel: Also known as printer port or Centronics port, this is an IEEE standard I/O connector.
    

    Parallel Port & Connector

    Older printers use this type of connection where the data is sent to the printer in a parallel form. This connector is now almost completely replaced by the common and fast USB port.

14. Serial/RS232 (Recommended Standard 232): It is a standard I/O port for serial binary data signal transfers. Usually found on older computers (but supported on most new ones via a riser),
    

    Serial Port

    it was commonly used to connect modems, and mice, and was popular as a way of interfacing with programmable electronics projects.

15. USB (Universal Serial Bus): It is a serial bus standard used to connect devices to a host computer. Used commonly by peripherals such as keyboards, mice, printers, scanners, modems, storage devices and so on, the highest data transfer speeds by USB are up to 60 MB/s.
    

    USB Port

    This is today the most common and easy-to use interface for peripherals.

16. Mini USB: This is functionally no different from a regular USB connector, but is a lot smaller in size. Mini USB connectors are commonly used for smaller devices such as portable storage devices. MP3 players, cameras, etc.
    

    Mini USB

    Micro USB is still smaller than the mini USB and is used for much smaller devices and gadgets such as MP3 players, mobile phones/PDAs which have no space even for mini USB.

17. SATA (Serial Advanced Technology Attachment): It is used for hard drives and optical drives inside the computer like PATA used to be, but is alot faster than the older PATA.
    

    SATA Port & Cable

    The SATA interface can transfer data at speeds of up to 3 Gb/s.  SATA ports are found on motherboards and add-on drive controllers.

18. eSATA (External Serial Advanced Technology Attachment): It is similar to SATA, but is used externally unlike the former which is used internally.
    

    eSATA

    eSATA is used to connect an external hard drive directly to the computer’s motherboard for incredibly fast data transfers.