Identifying people or objects with a computer may seem like an easy task, but, in reality, there is a lot of technology behind the devices used to accomplish this task.
In this chapter, we are going to use a smart card reader and two kinds of RFID readers (a Low Frequency or LF reader suitable for short ranges and an Ultra High Frequency or UHF reader suitable for long ranges) in order to show different possibilities to implement a minimal identifying system for access control.
Once the detection has been done, the system will send a message to our Twitter account informing our followers about what is happening (in a normal case, we may lock or unlock something, but I decided to do something different).