Composer is a tool for dependency management in PHP. It allows you to declare the libraries your project depends on and it will manage (install/update) them for you. It is a dependency manager It enables you to declare the libraries you depend on. Finds out which versions of which packages can and need to be installed, and installs them (meaning it downloads them into your project). composer init - to launch a wizard composer require - to add a dependency, also creates a composer.json to manage dependencies composer.lock - this file ensures that everyone in the project uses the same version of the packages by not allowing newer versions to be downloaded This is one of the most frequently asked PHP interview questions and answers for freshers in recent times.