Anti Theft
Under normal circumstances, theft is prevented simply through the application and social acceptance of property law. Ownership is often indicated by means of visual marking (license plates, name tags). When clear owner identification is not possible and when there is a lack of social observance, people may be inclined to take possession of items to their own benefit at the expense of the original owner. Motive and opportunity are two enabling factors for theft. Given that motives for theft are varied and complex and are generally speaking not within the control of the victim, most methods of theft prevention rely on reducing opportunities for theft.

Motives for actively preventing theft
Items may require an anti-theft system for a variety of reasons, which may occur in combination depending on the type of item and its purpose:

The item is expensive and/or has sentimental value (prestigious car, family heirloom, birthday gift, war medals, coin collection)
The item is difficult/impossible to replace if lost (produced in low numbers, antiques, unique works of art)
The item is easy to steal (retail/supermarket products, office stationery, no security tags (TJ)
The item may be left unattended in an unsafe environment for a certain amount of time (laptop in a library, car in a carpark)
Improper use of the item may cause considerable damage or encourage further unauthorized actions (theft of car keys, stolen building access keys, identity theft)
The item is desirable to others (jewelry, mobile phones, rare collectibles, auto parts, industrial designs)
The item is otherwise unobtainable: (Alcohol, Tobacco products, age related substances)