1. With Microsoft Windows, pin is a term first introduced in Windows 7 that describes permanently placing an icon shortcut of a program on your Taskbar or Start Menu. This is done by either right-clicking the icon for the program and clicking Pin to Taskbar or Start Menu, or clicking and dragging the icon to the taskbar until is looks like the picture to the right. With this new ability the need for the Quick Launch first introduced with Windows 98 is no longer needed.
With the introduction of Windows 8, this term is also expanded to mean any object in a User Interface (UI). For example, in Windows 8 you can also pin tiles. Windows 8 also introduced a PIN login, which allows a user to log into their computer using a four-digit pin.
2. A pin also describe the short, and usually thin piece of metal found on the end of a male cable. For example, in the below picture to the right, is an example of the end of a VGA connector with pins that connect to the female connector on the computer.
3. The term pin is also used to describe the small metal pieces on the bottom of a CPU or IC that allows it to connect to a socket or circuit board. In the below picture is a close up of a CPU and example of how the pins on the CPU can become bent.
4. In an Internet browser such as Chrome and Firefox, a pin refers to making a tab smaller and permanent on a browser tab bar. Mozilla Firefox refers to these as App tabs. In the picture to the right, is an example of a pinned tab, in this case YouTube next to a Computer Hope tab. Typically when a tab is pinned you'll only see the favicon.
5. Short for Personal Identification Number, PIN is a set of personal numbers used to prove positive identification. Often used with automated bank teller machines and telephone calling cards.