Electronic article surveillance (EAS) is a technological method for preventing shoplifting

Shoplifting

Shoplifting is theft of goods from a retail establishment. It is one of the most common property crimes dealt with by police and courts....

 from retail store

Retail

Retail consists of the sale of physical goods or merchandise from a fixed location, such as a department store, boutique or kiosk, or by mail, in small or individual lots for direct consumption by the purchaser. Retailing may include subordinated services, such as delivery. Purchasers may be...

s or pilferage

Package pilferage

Pilferage is the theft of part of the contents of a package. It may also include theft of the contents but leaving the package, perhaps resealed with bogus contents. Small packages can be pilfered from a larger package such as a shipping container...

 of book

Book

A book is a set or collection of written, printed, illustrated, or blank sheets, made of hot lava, paper, parchment, or other materials, usually fastened together to hinge at one side. A single sheet within a book is called a leaf or leaflet, and each side of a leaf is called a page...

s from libraries

Library

In a traditional sense, a library is a large collection of books, and can refer to the place in which the collection is housed. Today, the term can refer to any collection, including digital sources, resources, and services...

. Special tags are fixed to merchandise or books. These tags are removed or deactivated by the clerks when the item is properly bought or checked out. At the exits of the store

Store

Store may refer to:*a retail store*a place where things are stored, e.g. a ship's paint store*expendables released from an aircraft, such as ordnance or countermeasures*Štore, a town and a municipality in eastern Slovenia...

, a detection system sounds an alarm or otherwise alerts the staff when it senses active tags. For high-value goods that are to be manipulated by the patrons, wired alarm clips may be used instead of tags.
There are several major types of electronic article surveillance systems :

• Magnetic, also known as magneto-harmonic
• Acousto-magnetic, also known as magnetostrictive
• Radio frequency
• Microwave
• Video surveillance systems(to some extent)

These tags are made of a strip of amorphous metal

Amorphous metal

An amorphous metal is a metallic material with a disordered atomic-scale structure. In contrast to most metals, which are crystalline and therefore have a highly ordered arrangement of atoms, amorphous alloys are non-crystalline...

 (metglas) which has a very low magnetic saturation value.