In this video, an RFID and GSM based attendance system using Arduino and DS3231 RTC Module. We can use this project for taking the student’s and office employee’s attendance or when they join and leave the work. The working principle of this project is when you put a tag on the RFID reader, it scans the tag, and the Arduino controller sends an SMS with help of the GSM module to the predefined number when you are joining or leave.