A PHP developer is a software developer who specializes in using the PHP programming language to build web applications and websites. PHP (Hypertext Preprocessor) is a popular server-side scripting language that is widely used for web development. The primary role of a PHP developer is to write server-side logic, develop back-end components, and integrate the application with front-end components. They work with databases, handle data input and output, and implement security measures to protect the application from vulnerabilities. PHP developers often collaborate with front-end developers, designers, and project managers to create functional and visually appealing websites and applications.