To understand what SharePoint does for businesses, it is important to understand collaboration. To collaborate by definition, is to work jointly together with others especially in an intellectual endeavor. SharePoint allows companies to have a common interface allowing companies to function together in teams which can be made up of internal employees, customers, vendors, and other business partners. It allows these teams to communicate and share information securely with one another.

Some of the key features include document management, advanced index and search capabilities, project tracking, dashboards and business intelligence, integration with other applications and data sources, connections to Word, Excel, Outlook to share documents, email, calendars, task-lists and much more. Workflows can be used to automate processes and simplify tasks.

It grows as the organization grows, allowing businesses to start simple and develop more advanced uses as they become familiar. Out of the box, it provides benefit almost instantly and provides a framework which can be leveraged to build sophisticated applications.

Below is a video produced by Microsoft which explains in more detail.