HTML is a markup language used to structure and present content on the web. It contains tags that are used to define headings, paragraphs, links and other elements. HTML tags usually come in pairs with an opening and closing tag. Some common body tags include <h1> for main headings, <p> for paragraphs and <a> for links. HTML also supports basic text formatting using tags like <b> for bold, <i> for italics and <u> for underline. The development of HTML standards has progressed through several versions since its invention in 1989 to its current form with HTML5.