Types of Computer Connectors

A computer can look like a box with a lot of confusing wires connected to it. But often connections are color coded, as is the case for audio input and output on the back of many computers. Some plugs, such as telephone modem and power cords, only fit in one socket, so it's not too hard to figure out where they go. Here's a look at the most common computer connectors and their functions.
 
Power
Power connector - Photo credits: Jungar.net
The power cord connects the computer to the AC electric source. The male end of the cord goes into the wall outlet (or a power strip/UPS) and the female end plugs into the back of the computer.
 
Keyboard and Mouse PS2 connector
Two common types of plugs are used to connect keyboards and mice to the computer. The older connector, which has pins is called a PS2; it's on the end of the cable coming out of the keyboard or mouse. Often these will be in a color to match designated sockets on the back of the desktop CPU.
Many newer keyboards and mice use standard USB ports. Most devices that are external to the computer today use USB ports as a convenient way to make the connection. To comply most new computers have four or more USB ports, some mounted on the front and some on the back.
 
USB USB connector
USB (Universal Serial Bus) uses a technology termed "plug and play." These connectors can be "hot-plugged," that is, connected and disconnected while the computer is on. Pictured is the end of a USB Type A connector, which goes into the computer. A more square-shaped, smaller USB Type B connector is typically found on the other end. This fits into the peripheral device, such as a camera or scanner. Some newer cameras use a tiny version of these plugs, called mini-USB connectors.
 
Monitor Monitor cables
The traditional VGA style "D" pin connector is still common for connecting computer monitors to computers. Some newer flat-screen monitors also use a similar-looking plug called a DVI video plug (digital video). A monitor may also have a socket for connecting a DVD player through an "S-video" jack, which is a round pinned plug.
 
Firewire Firewire connector
Firewire (IEEE 1394) ports are for high-speed connections. Digital camcorders and external hard drives often have firewire ports.
 
RJ-11 and RJ-45 RJ-11 phone/modem connector
For connecting modems to telephone lines, RJ-11 plugs are used, which are standard 4-pin telephone connectors. Similar in appearance but slightly wider and with more pins, the RJ-45 connector is used for Ethernet connections, such as cable modems. 

Fast Becoming Obsolete Connectors Parallel printer cable connector
As technology has advanced, new more efficient devices use new types of connectors. Several connectors that were once essential are now obsolete on new computers. An example is the parallel printer cable, with a DB25 male plug on one end to connect to the computer (in the COM 2 port) and a CN36 male on the other end to plug into the printer. Most printers today connect to computers via USB ports.

Another cable that is being phased out are serial connectors (RS-232). A male DB9 connector was typically found on the CPU, and modems and early digital cameras plugged into this connection.