This document discusses using PHP and MySQL to create a campus library search engine mobile app. PHP will act as an interpreter between the Android app and remote MySQL database, allowing data to be stored, retrieved, updated and deleted efficiently from the database. XAMPP will be used to host the MySQL database and PHP scripts locally for testing, mimicking a live server. The app will allow users to register, log in, and retrieve book information from the MySQL database through interactions with PHP scripts from their Android device.