What is composer?

Composer is a tool that makes it easy for PHP developers to use libraries and code written by others. Instead of manually downloading and organizing code packages, Composer lets you declare what libraries your project needs and automatically downloads and manages them for you. Think of it like npm for Node.js or pip for Python. When you're building a PHP application, you often need third-party libraries to handle common tasks, database connections, email sending, form validation, and so on. Without Composer, you'd have to find each library, download it, figure out where to put it in your project folder, and keep track of which version you're using. Composer automates all of that. You write a simple text file listing what you need, Composer fetches everything, and it handles version conflicts automatically. Developers use Composer by creating a configuration file that lists their dependencies, then running Composer commands to install and update those packages. Composer also figures out which versions of packages work together, so if library A needs version 2.0 of library B, but your project asks for version 3.0, Composer will alert you to the conflict and help you resolve it. Once everything is installed, Composer generates a loader file that your application uses to access all those packages, so you don't have to manually include each one. The project has been around long enough to become the standard way PHP developers manage dependencies. There's a central package registry called Packagist where developers publish their libraries, making it easy to discover what's available. The tool itself is maintained by maintainers Nils Adermann and Jordi Boggiano and has become foundational infrastructure for modern PHP development.