Desktops come in a variety of shapes and sizes; these varied dimensions are known in the industry as "Form Factors".
To help you decide which Form Factor is right for you, we will run through the pros and cons of each option:
This is the largest size of desktop, and often, the name "desktop" can be misleading; due to their size, this style of desktop would likely to be more at home beneath your desk. This type of desktop is ideal if you wish to have plenty of room to upgrade your computer in the future, and space is not an issue.
|Small form factor (SFF)
Despite its name, this style of desktop is closer to a medium size. Smaller than the tower style desktop, it fits unobtrusively into most workspaces, either stationed vertical next to your monitor or placed horizontally beneath your monitor to free up extra room. This is the Form Factor most commonly found in offices throughout the UK.
|Ultra Small-Form Factor (USFF)
This is one of the smallest desktop types commonly available. Expansion options on this style are limited; the aim of the USFF desktop is to build a computer into as compact a chassis as they can. These are useful where space is at a premium or in situations where you would prefer the desktop to remain unseen (some can even be bolted onto the back of your monitor via the "VESA mount": the interface on the back of your monitor used to mount your monitor onto a wall or arm)
Additional Points to Consider