An anti-theft system is any device or method used to prevent or deter the unauthorized appropriation of items considered valuable. Theft is one of the most common and oldest criminal behaviors. In addition to the initial obtainable cost of an item, the cost of replacement or recovery from theft of the item is usually considered when considering the cost of installing an anti-theft system. This cost estimation usually determines the maximum cost of the anti-theft system and the need to secure it. Expensive items will generally be secured with a higher cost anti-theft system, while low-cost items will generally be secured at a lower cost. Insurance companies will often mandate a minimum type of anti-theft system as part of the conditions for insurance.