HTML documents are files with the file extension *.html, which stands for HypertextMarkup Language. They are files for websites. HTML documents can be opened with all common browsers or with an HTML editor. The browsers or HTML editors read the HTML tags and create a web page from them.
The general structure of an HTML document consists of the document type declaration, the header data and the body data. The document type declaration is a function that supports browser rendering. It switches the browser into the default mode. The header data contains the title of the web page. All texts and commands occurring on the web page are specified with the HTML tags. In addition to the title, these include the metadata, character encoding, links and cascading style sheets( CSS).