These tags do not add anything to the display but are more there for convention. Certain tags go into a certain section of the HTML document.
The <TITLE> tag puts a title at the top of the browser window. This allows you to define the exact title you want in the document. The tag appears within the <HEAD></HEAD> block of information.
<TITLE> is also used a the link information when a user saves a Web document into a bookmark.
See an example (The skeleton of an html document.)