Card readers are electronic devices that are used to control access to a property. They are commonly used in conjunction with access control systems, which are designed to regulate and monitor the movement of people and vehicles in and out of a secure area.

There are many different types of card readers available, and they can use a variety of technologies to authenticate cards or fobs. Some common technologies include radio-frequency identification (RFID), magnetic stripe, and smart card technology.

Card readers can be used in a variety of applications, including residential gates, commercial buildings, parking garages, and government facilities. They are typically used to grant or deny access to authorized personnel, and can be used to track and log activity for security and auditing purposes.

Card readers can be added and deleted easily, depending on the system that you purchase. Some systems allow you to add or delete cards onsite, using a control panel or computer. Others may allow you to do this remotely, using a web-based interface or smartphone app.

In summary, card readers are electronic devices that control access to a property using a card or fob. They are commonly used in access control systems and can be added or deleted easily, depending on the system.