Electronic article surveillance (EAS) refers to
|“||[s]imple electronic tags that can be turned on or off. When an item is purchased (or borrowed from a library), the tag is turned off. When someone passes a gate area holding an item with a tag that hasn't been turned off, an alarm sounds. They can be RF-based, or acousto-magnetic.||”|
EAS is used widely to prevent shoplifting from retail stores or pilferage of books from libraries. Special tags are affixed to merchandise or books. These tags are removed or deactivated by the clerk when the item is properly bought or checked out. At the exits of the store, a detection system sounds an alarm or otherwise alerts the staff when it senses an active tag. For high-value goods that are to be manipulated by the patrons, wired alarm clips may be used instead of tags.