What is Sharepoint and what are its uses?

in simple word we can describe SharePoint as a business collaboration and document management platform for the companies and the web from Microsoft.

But in depth, it is not easy and simple to understand as it not just a single thing, it is a wide collection of different technologies. For example, it is like learning MS Office, so once you start to learn MS word then you have to learn MS excel, MS Access and so on.
Suya