Access control, also named door entry access control systems, or access control management system, it known as a digital intelligent management system for personnel access . Usually,access control systems can be divided into three categories as Password access control systems, card access control systems, biometric access control systems.

1. Password Access Control System
Inputing a password,verify password sucessfully and send a relay signal to drive electric lock, then open the door.
Advantages: Just remember your password, without the need to carry other media. With low cost.
Disadvantages: password inputing speed is slow, generally it require several seconds to input the password. So if the user quantity is large ,many people need to queue and wait. If some users input wrong passwords, they need re-input and take longer time. Poor security level, user’s password is easy to remembered by others who is next to you.

2. Card Access Control Systems
According to different card type,it is divided into the contact card access control systems (magnetic stripe card access control, barcode card access control ) and a non-contact card access control system(also known as proximity cards access control, RFID card access control) . Contact cards are easy to be worn and damaged, can not be used frequently, the range of use has become less and less. Non-contact IC card,ID card are much more popular , because of its durability, economical , fast reading speed and high security. Therefore, the proximity card access control system widely used in security area.

3. Biometric Access Control Systems
According different people’s biometric features to verify identity . Generally,it including thumbprint access control system , palm access control system, iris access control systems, face recognition access control system,vein recognition access control system . Advantages of biometric fingerprint access control systems are: no need to carry cards and other media, less chance of repeating, is not easily replicated, high safe level .