Begining to Sharepoint

Share point portal server:

As the volume of intranet content grows, administrators and users are increasingly looking for ways to manage the volume of information. Just as Netscape aggregated the then-growing internet content into a manageable framework (called a portal), application vendors have created many packages that allow their customers to aggregate their intranet content into corporate portals.

Like most portal products, SharePoint allows visitors to create custom views of the Web site. This customization can be very simple or very complex, depending on the type and version of the product that is installed. In addition, SharePoint has a powerful collaboration model that is tightly integrated with the Office 2003 suite.

The current version of SharePoint is its third (despite its name).
Check this link for more details:
http://www.intranetjournal.com/articles/200502/ij_02_04_05a.html

Share point Foundation:

SharePoint Foundation 2010 provides a Web-based collaboration platform that's more secure and easy to manage. With SharePoint Foundation, your people can quickly access the documents and information they need to make good decisions and get work done.
http://sharepoint.microsoft.com/en-us/product/Related-Technologies/Pages/SharePoint-Foundation.aspx