Because proximity cards are so convenient, people who use them rarely want to learn more about how they work or how they came to be the preferred smart card alternative to reader devices. Most people just know that somehow the card is detected when it moves past a sensor, and it gives them access to a secure account or physical space. These cards are different from the previous family of access cards with magnetic stripes. They can hold much more data, and sensors can usually detect them through the material on a pocket, wallet or purse.
Proximity cards have even gained ground in banking and retail shopping. Many merchants have already made the switch from card readers as a way to keep purchases more secure. The number or large scale hacking incidents that have occurred in recent times has forced the retail industry as a whole to pursue more secure means of conducting transactions. New laws have shifted the liability for consumer financial loss from hacking to retailers, if they do not upgrade pay stations with proximity card capabilities.
So far, technology designers have created two types of proximity cards. The passive card uses a radio frequency signal. Someone who has a proximity card of this type has to stand close to the sensor in order for their card to be detected. The active proximity cards have a much wider range of about 500 feet. A typical use for them is automatic toll stations. A sensor detects a pass card as a car is passing and deducts the fare from a monthly account.