As the world becomes less secure, businesses and consumers are becoming more aware of their own security measures and the options available for controlling their premises. Access control systems have evolved greatly over the past 10 to 15 years in a direct response to this need in the marketplace. Access control systems allow businesses or homeowners to regulate entry into buildings or portions of buildings using electronic rules that are set at the individual level. Door access control can be set to "permit access" for an individual through a specific door on certain days of the week, at certain times during the day, with certain credentials, or a combination of all three. Usually, basic systems employ a scan-able badge or radio frequency ID, but more sophisticated systems utilize biometric access control. On these high-tech systems, entry and exit is controlled by a person's scanned retina or fingerprint. Reputable sellers on eBay offer a number of customizable access control systems and associated components.