Computer Ports

Input and output ports allow users to connect hardware, such as monitors and keyboards, to a computer. The figures below were taken, by in large, from Desktop examples. Laptop ports are usually smaller in size.

Power – Desktop
Computers require a grounded (three prong) power outlet for proper operation. 
The Universal Serial Bus (USB) port is the most versatile interface used on modern computers. USB ports can be used to connect mice, keyboards, printers, scanners, cameras, external hard drives, network switches, and more. There are three speed specifications for USB ports: USB 1.0, 2.0 and 3.0. USB ports come in six different forms: USB A, USB B, Mini-A, Mini-B, Micro-A, and Micro-B.
USB Type-C
USB Type-C is a new port designed to use a reversible connector. Its use is not common yet and only a handful of devices have been built to use this port. One such device is the 2015 Apple MacBook.
Network/Ethernet (RJ-45)
The port used for networking on most modern computers is typically referred to as an Ethernet port, but may also be called a RJ-45 jack, network port, or Cat5 port. The variety of names comes from the fact that most modern computers connect to Ethernet networks using category-5 twisted pair cables, which plug into RJ-45 jacks.
Sound ports in computers can be used for headphones, speakers, or microphones. These ports are often color-coded and marked with icons that represent their use.
The Video Graphics Array (VGA) port is used exclusively for video, and has been the main PC-video interface for over 15 years. This port is being replaced by Digital Video Interface (DVI) ports, and DVI-VGA adapters are available.
The DVI port is used for video on newer monitors. There are multiple versions of DVI that have a slightly different form or pin layout.
The HDMI is a higher-end video port. Alienware and the MAC mini were some of the first computers to come standard with these ports. This port can also handle audio input.
Display Port
The Display Port is an alternative to the HDMI port and appears on select laptops and other devices. In addition to being able to carry video, it can also carry audio and USB data. It is backward compatible with VGA and DVI through the use of adapters. An adapter can be used to allow HDMI cables to be used as well.
Mini-Display Port and Thunderbolt 2
The Mini-Display Port and the Thunderbolt port have the exact same shape and size, but it is important to keep in mind that a Mini-Display Port will not work with a Thunderbolt connected device. These ports are used by Apple computers to accomplish a wide range of data transmissions including video signals, audio signals, and high speed data transfer. Apple has built a number of adapters that can be connected to this port, including Gigabit Ethernet, VGA, DVI, and USB.

Historical/Older Computer Ports

The parallel port, also known as a DB-25 port, is primarily for printers/scanners, and is often referred to as the “printer port”. The parallel port is currently being phased out, with most printers interfacing using a USB port.
The serial port, also known as a DB-9 port, is an older port that was used in the 1980’s for a variety of peripheral devices. In the 1990’s, it was used primarily to connect mice, joysticks, and modems. The serial port is almost completely phased out – some desktop computers have serial ports since they have motherboard components in common with the parallel port.
The PS/2 port was developed by IBM to connect keyboards and mice. Computers will usually have 2 of these ports, one purple (for the keyboard) and one green (for the mouse). PS/2 was the standard for about 15 years, but is now being replaced by the USB port.
Firewire (IEEE 1394)
Firewire, also known as IEEE 1394, was developed by Apple Computers in 1995. “Firewire” is a trademarked term, and other companies use the same technology under different names. Firewire is used for many devices and was much faster than its contemporary, USB 1.0, but has similar speeds to USB 2.0. Firewire never reached the popularity level of USB, and has since been dropped by Apple on iPods (but not on their computers yet).
Modem (RJ-11)
The modem was the primary way to access (dialup) networks in the 80’s and 90’s. With broadband (cable and DSL) networks replacing dialup, many modern computers do not come with modems.

Which devices can these ports be found on?

Display PortYesYesNoNo

Ports are typically found on the front and back of desktops, and the sides of laptops, tablets, and smartphones.

Note: This may not be true for all models