Check your version
This tutorial covers a topic in Drupal 8 which may or may not be the version you're using. We're keeping this tutorial online as a courtesy to users of Drupal 8, but we consider it archived.
Alternate resources
This tutorial is for PHP developers—including Drupal 7 developers—who want to get a local development environment up and running for Drupal 8 development work. In this tutorial, we will install Drupal 8, fire up the built-in PHP web server, set some variables in php.ini, initialize a Git repository, and discuss how Composer will impact what you commit to Git now and in the future. Finally, we'll walk through how to configure PhpStorm for Symfony development that plays nicely with Drupal 8 projects as well.
Additional resources
Development Environments
Local Development Guide (drupal.org)
PhpStorm
The Wonderful World of Composer — Drupalize.Me
PHP's Built-in web server (manual) — php.net