Help:Templates
Templates are standard wiki pages whose content is designed to be transcluded (embedded) inside other pages. Templates follow a convention that the name is prefixed with "Template:", assigning it to that namespace. Therefore you can create them like any other wiki page. (Ref: http://www.mediawiki.org/wiki/Help:Templates)
Intelligent use of Templates will be very much effective to highlight important information on your wiki pages. To transclude (embed) a template on your page you have to use the tag {{template name}}, that is, type the template page name within two curly braces at the required position on your page and save it. This action would fetch and display the template contents on your page.
However filling the entire page with templates may not be a good idea.