In this chapter, we will explain how to use the application-level package manager with the most popular e-commerce platform. Being inspired by Node.js npm, Composer provides a unified format that simplifies dependency management of PHP software. The usage of Composer in various Magento 2 projects is inevitable, because it is a part of the platform. You can run the package manager through the command line, installing dependencies for your modules. Besides, Composer provides the ability to install Magento 2 extensions available on Packagist (the repo is described below). Another important feature introduced in Composer is a set of autoload capabilities for libraries that essentially simplifies the usage of third-party software solutions.