What is Twig?
Twig is a PHP templating engine. This means you can build separate components and reuse them within your site. For example, you only need to build a header or assemble a product grid once.
The Twig code is interpreted by PHP and supplemented with data from the database. How to do this will be covered later.
Some important concepts to understand are:
Tags
Filters
In addition to the Twig documentation, there are also a number of custom filters explained on the filters page of this document.