A: There are several methods and technologies, as we describe below, to control who enters or leaves a place but the question is, which method or technology is the best. No matter what method or technology you use, there is a prerequisite; you need a physical barrier of the entrance/exit that you need to control and which can be locked either with an electrical lock, an electromagnetic lock or an automated opening/closing mechanism. In addition, you need to evaluate what the necessity of having such a system is and what the benefit will be, as these two factors will determine how much someone is willing to invest in such a system. Below we lay out several options:

a. Stand Alone Access Control. Usually, this is the most cost-effective way to control an entrance/exit as such a system will require the minimum hardware. You will merely need a power supply to power up the system, as well as the access control module which is usually installed outside the entrance. These access control modules are usually alphanumeric keypads that can be programmed to work with user codes. The installer or master user (owner) will set the user codes and once the code is entered the module will open or release the entrance. Another type of access control modules is the proximity RF readers. These modules will work with RF cards and/or RF Key tags. The installer or master user (owner) will memorize/program the authorized RF cards/key tags and only those users that hold and present the cards or tags to the reader will be able to open or release the entrance. Whilst this technology/method is the most simple and cost-effective one, there are some drawbacks related to it. The system can easily be bypassed and it is hard to manage (say in case an RF card is lost and you want to delete it or deactivate a card for any reason). Now you can easily find access control modules that will combine both alphanumeric keypad and RF readers.
b. Stand Alone Access Control with biometrics: The same as above but will work with fingerprints, eye scanning and other biometrics.
c. Computer Based Access Control. This type of technology will be used for larger scale applications, where the need for controlling an entrance is more complicated and demanding. Usually, the need is to control multiple entrances and most significantly to record down data like time, date, entrance and user idy that has operated the entrance. The importance of having a more secure, hard to bypass, system is also significant. These systems will incorporate a central processing unit where everything is connected and managed by software. The cost for this type of systems is comparatively higher than stand alone systems.
d. Video and Audio Door Phone systems. Frequently found in domestic applications where the need for controlling an entrance is less complicated and demanding. All you need is to view and talk to the person that requests to enter. If this person is “welcomed”, the door will unlock via the system.