With Design Manager, you can convert an.html file into a SharePoint 2013 master page, a .master file. After the conversion, the HTML file and master page are associated, so that when you edit and save the HTML file, the changes are synced to the associated master page.
Thimble projects are hackable webpages that allow you to complete a challenge, play a game or build something cool by editing the code of the page, and learning webmaking skills like HTML and CSS in the process.
Every file is heavily commented and provides a lot of information about what code is necessary for various SharePoint functionality and content.
How to get the Content Query Web Part to output desired HTML.