How Web Part interact with SharePoint ?

Source: http://www.how2sharepoint.com/2010/05/how-web-part-interact-with-sharepoint.html

Help build reusable components that can be personalized and customized according to business user. We make our own webpart or we can reuse the existing one from SharePoint itself.

1. Data View Web Part - Displays data with rich design support through Microsoft SharePoint Designer.
2. List View Web Part - Helps us to display list content for any list in the SharePoint site.
3. Image Web Part - Helps us to display image files.
4. Members Web Part - Helps us to display members of the site.
5. Page Viewer Web Part - Displays web page in an Iframe.

WebPart is just a simple class that inherits from System.Web.UI.WebControls.WebParts. In other words one can say a kind of WebPart is WebControl that can be implemented in a WebPartZoneControl.

WebPart control is like driver manager keeps cases WebPart. Add WebPartZone WebParts to get ASP.NET pages when initialized.