SharePoint 2010, the “Wheel” ..
In case My previous Post got your attention, my guess would be that you’ve done a small online search about SharePoint, I would also guess you have seen this picture somewhere and wondered what does it mean, that’s what we are going to talk about in this post.
This Image represents Services offered by SharePoint, in other words, what can SharePoint do for you.
Lets start with “Sites”; SharePoint makes websites, I guess its obvious for anybody ! you can call it as a massive website Engine, you don’t need to be a programmer or web designer to create a Site, you simply choose a template and simple clicks and BAAM, you have a site.
Unlike most of websites among the Internet, users not only are readers in SharePoint Sites, they can edit pages, add pictures, change content, and so many options will be mentioned in later posts.
As for the term “Communities” SharePoint helps you work with other people, it can offer a collaboration Environment for its users, company wide Wikipedia’s, team sites, shared calendars, task lists, document can be edited by several people and so on.
This Huge product gives you a place to save your “Content”, Pictures, videos, Documents, as well as Sharing them with others.
So, when Contents keep growing to be large one, you certainly need some kind of “Search” engine to find what you want as fast as possible, SharePoint have that service for you too, it has a very complex Search Engine that you can set it’s policies by yourself, it can also search for people.
You will be no longer working with data in the old conventional ways, using “Insights” you can present data in very un-manual advanced ways, presenting data in ways that actually makes sense. Visio diagrams, spread sheets, dashboards and business intelligence systems. making it easier to make decisions based on the results.
SharePoint has capabilities to be extended, again, “Composites” helps you do that, you don’t have to be a programmer, you can use tools and programs such as Visio and SharePoint designer to build business workflows without writing code for instance.
It seems like I’ve talked a lot, but this is nothing compared to the options and services offered by SharePoint, you can spend months learning one section of those if you decided to go deeper, you can choose your way and be professional at it 
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this link might help you more : SharePoint Wheel
Hope this post helped you knowing more What SharePoint is, more is coming, stay tuned.
also you can read :
SharePoint baby steps (1) on Mohamed Saleh, SharePoint MVP Blog
Lets SharePoint 