The Hyper-Text Markup Language is the work-horse of the internet. HTML5, the newest derivative, has added much improvements based upon the commercial needs of the web.
I can hand-code HTML from a text-editor like Notepad or VIM. However, using contemporary tools which provide more robust execution and code-completion is far more efficient. Some tools, like Stylizer, assume that you have a proficiency in the language by leaving most interface commands to the keyboard.