HTML document is a term that refers to a variety of file formats that contain web page content, including text and multimedia components. Some of the synonyms for an HTML document include web page, webpage, HTML page, HTML file, HTML code, and web document. Each of these terms is used interchangeably to describe the same basic type of file. HTML documents are the backbone of the internet, since they provide the structure for nearly every web page on the world wide web. As such, they are an essential tool for website designers and developers, whether they are creating simple pages or complex sites with advanced features and functions.