I already have a web site, why would I need SharePoint™

From mail2web.com Wiki

Windows® SharePoint™ Services is more than just a website. SharePoint is a team based collaboration tool which allows you to share information and work in a team environment with other members of your company, group, organization, or even with your clients or vendors. SharePoint is not meant to replace your traditional web site or web store, but instead to present you with team based, organizational tools. Once your SharePoint site is activated, you can start adding users and building your site right away. SharePoint also includes integration with the Microsoft Office Suite, which allows you to use your SharePoint site with software you are already familiar with and use on a day-to-day basis.