Printed information around us whether in the form of newspaper, magazine, books or printed forms; are divided into small parts like a magazine into articles and each article has its own heading, sometimes a summary and then followed by the article which is further divided into paragraphs. Similarly a web site has many web pages composed of images, text, links to other pages and audio or video for an enriching experience.
Web is a collection of documents that all link together, and bear a strong similarity to the printed documents around us. Web pages are written in HTML (Hypertext Markup Language) or XHTML (eXtensible Hypertext Markup Language). Both are document-layout and hyperlink-specification language. They define how to display the contents of the document, including text, images, and other support media. The language also tells how to make hypertext links, which connect document with other documents.
In keeping with the principle of separation of concerns, the function of HTML is primarily to add structural and semantic information to the raw text of a document. Presentation and behavior are separate functions, which can be added as desired, ideally through links to external documents such as style sheets, graphics files, and scripts.