HTML

See also: Cascading Style Sheets, JavaScript, awesome-html5

• Mozilla Developer Network: HTML
• hackr.io: Learn HTML5
• HTML5.org – The Web Platform
• Google Web Fundamentals
• Dive into HTML

• Head First HTML with CSS & XHTML (O'Reilly, 2005)

Free as in beer and as in freedom. There's no use for HTML themes you can't legally modify.

• HTML5Up! – responsive, sleek HTML5 themes.
• HTML5 Boilerplate – minimal set of HTML to make a website look the same in most browsers.

Build a rough web template in a few clicks.

• GrapesJS
• LayoutIt

• Pixelarity
• Themeforest HTML templates
• Creativemarket HTML+CSS templates

• tidy – console application, corrects and cleans up HTML and XML documents by fixing markup errors and upgrading legacy code to modern standards. Can also just pretty-print without fixes.