Markup

HTML markup consists of several key components, including elements (and their attributes), character-based data types, character references and entity references. Another important component is the document type declaration, which triggers standards mode rendering.

The Hello world program, a common computer program employed for comparing programming languages, scripting languages and markup languages is made of 9 lines of code, although in HTML newlines are optional:

markup languages in 9 codes

The text between (html) and (/html) describes the web page, and the text between (body) and (/body) is the visible page content. The markup text '(title>)Hello HTML(/title)' defines the browser tab title