A Web Template or Website Template is pre-formatted in HTML so you can build website much more easily. Most templates are built from web designers that add some type of back end interface to make it easier to adjust or change the content on the website where the template is placed. Using a web design template will speed up productivity because there is less time in the production of a website. Templates sometimes come with extra functions to make the website more appealing. Many web templates are free. There are also paid or premium web templates. Premium web templates are licensed so you can not share them. Web Templates are also used with Content Management Systems (CMS) like WordPress, Joomla, or Drupal.
For more information see: http://en.wikipedia.org/wiki/Web_template_system.