Composer is the dependency manager for PHP. Use packagist.org to search for packages.
Here the basic commands for composer:
Start new php project:
Install a new packages with:
composer require packageName
Get the latest version
composer remove packageName
composer search packageName
Shows a list of installed packages that need to be updated:
You should always run the validate command before you commit your composer.json file, and before you tag a release.
CLI documentation here.