If you have any exposure to other text-based template languages, such as Smarty, Django, or Jinja, you should feel right at home with Twig. It's both designer and developer friendly by sticking to PHP's principles and adding functionality useful for templating environments.
The key-features are...
Twig is used by many Open-Source projects like Symfony, Drupal, eZPublish and many frameworks have support for it as well like Slim, Yii, Laravel, Codeigniter,silex and Kohana — just to name a few.
Installation
The recommended way to install Twig is via Composer:
For php 5.x users
composer require "twig/twig:~1.0"
For php 7.x users
composer require "twig/twig:~2.0"