Online Airline Reservation System eases the process of airline ticket booking for users. This project allows users to create and modify accounts. It allows users to book their tickets, cancel their tickets within a stipulated four-hour time and view their past travel history. Furthermore, it updates upcoming flight status to the users in case of any delay. The website and MySQL database are managed by an admin. Admin has the authority to add flight, delete flight, add airplanes, delete airplanes, change airplane assigned to a flight and modify the arrival and departure time of flights. The front-end of the website is developed using HTML, CSS, JavaScript and bootstrap. The server-side scripts are written using PHP. MySQL open-source relational database is used in this website to store data.