Hypertext Markup Language (HTML) is the basic programming language of the World Wide Web. It’s the common thread that ties together virtually every website, from large-scale corporate sites like Microsoft’s to single-page classroom projects at the local grade school. In simple terms, a webpage (or HTML document) is a plain text file that has been encoded using HTML so that it appears nicely formatted in a web browser. Here’s what HTML means, word-by-word: