To ensure the safety of electrical appliances commonly found in residential, commercial, and industrial locations, the United Kingdom requires that certain tests be carried out on a continual basis depending on the potential hazard of the appliance in question. The PAT test, or Portable Appliance Test, is used to designate potential appliances as hazardous, and others as fit for use and safe for anyone around. After a PAT test has been undergone, which includes such processes such as checking the internal electrical components for any possible danger, observing the external power cord, and taking notice of the environment in which the appliance itself it situated, then PAT labels are affixed to the machine with an indication as to how the appliance faired in the PAT test.

PAT labels are a very important role in Portable Appliance Testing and without them potentially harmful appliances wouldn’t be marked as such. Once testing has been successfully completed, a label is affixed to the appliance to allow for users and testers of the machine to know if a test has been performed, how the test turned out, and a number of other important pieces of information. The main and most important information that is displayed on a test label is the results of the test, and most commonly comes in three forms. The results of a PAT test can come in the form of ‘passed’, ‘tested for electrical safety’, and ‘DO NOT USE’, and this information can be coupled with the use of color coding to more effectively put across this information. The color green is most commonly used to denote an appliance as safe for use, as the color green is a fairly universal color denoting "safe", or "go". Labels with a red color, as red is a color typically interpreted as "stop" or "danger, is used to color certain PAT labels so that the danger of a ‘DO NOT USE’ result from a portable appliance test can be noticed from afar without the need to get real close to the potentially hazardous appliance.

PAT labels come in a variety of different forms, depending on what sort of appliance they are to be affixed to, their usage, and a number of other factors. These labels are also made to last, and usually comprise of a laminated surfaced and strong adhesive to ensure durability and that their message will stay right where it needs to stay. PAT labels are also available in different modes of application, such as ones that are meant to be wrapped around power cables, ones that are specifically designed to fit snuggly over plug tops, and the most standard labels which are simply labels with adhesive which act as stickers to display the pertinent information. There are also labels that are specifically used for the testing of microwaves, as microwaves are a very commonly used appliance and also quite potentially dangerous and their emission levels must be measured to ensure the user’s safety. These labels play an important part in safety awareness.