When a visitor to a website requests a particular page (by clicking on a hyperlink for instance) the HTTP server where the page is stored returns the HTML document to the user's computer and the web browser displays it. On a static web page, this is all that happens. The user may interact with the document through clicking available hyperlinks, but the document has no capacity to return information that is not pre-formatted within it. On a dynamic web page, the user can make requests (often through a form) for data contained in a database on the server that will be assembled 'on the fly' according to what is requested. For example the user might want to find out information about a theatrical performance, such as theatre locations and ticket availability for particular dates. When the user selects these options, the request is relayed to the server using an intermediary, such as PHP script embedded in the page's HTML. The intermediary tells the server what information to return. Such a web page is said to be dynamic.