Composer is a dependency management tool for PHP similar to npm for Node.js and bundle for ruby. It is not a package manager in the same sense as Yum or Apt are. Yes, it deals with “packages” or libraries, but it manages them on a per-project basis, installing them in a directory (e.g. vendor) inside your project. By default it does not install anything globally. It does however support a “global” project for convenience via the global command. It permits you to declare the subordinate libraries your task needs and it will install them in your project for you.