Although a web site may be a mix of the following, before starting a web project you should consider which category you're heading to.
Static Websites
Simple and cheap
Dynamic Websites
The ones you may update on your own
Display Websites
With photo galleries and stuff to please visitors' eyes
Interactive Websites
With tools to get your visitor involved
Promotional Websites
To get found on search engines
Special Websites
E-commerce, On and Offline catalogues, games and advergames, web radio, web applications...