Can you define what is SharePoint and some overview about this ?

SharePoint helps workers for  creating  powerful personalized interfaces only by dragging and drop pre-defined Web Part Components. And these Web Parts components also helps non programmers to get information which care  and customize the appearance of Web pages. To under stand it we take an example  one Web Part might display a user's information another might create a graph showing current employee status  and a third might show a list of Employees Salary. This is also possible that each functions has a link to a video or audio presentation.So now  Developers are unable to  create these Web Part components and make them available to SharePoint users.