Some Important

• Keep in mind that although site pages are loaded from a database, web parts and their user interfaces are not. Only the configuration of the web part is stored in the database 

• Site pages that are loaded from the file system are known as ghosted pages, and when these pages have been customized they are known as unghosted pages. 

• SharePoint 2003 brought us ghosting/unghosting; SharePoint 2007 scrapped these terms in favor of the more descriptive uncustomized/customized. Now with SharePoint 2010, the terms attached and detached are used to prevent any ambiguity. 

• Site pages and application pages is the way they are parsed by the SharePoint platform. Application pages behave like any other ASP.NET page in that they can contain inline server-side code; however, site pages are rendered using the safe mode parser that prevents inline server-side code from executing. 

• The client object model has three variants:

             1) JavaScript Client Object Model
             2) Silverlight Client Object Model
                          Microsoft.SharePoint.Client.Silverlight.dll
                          Microsoft.SharePoint.Client.Silverlight.Runtime.dll
             3) Managed Client Object Model:
                  This version has been designed for use by .NET-managed applications
                          Microsoft.SharePoint.Client.dll
                          Microsoft.SharePoint.Client.Runtime.dll

Communication from the client-side object to the server-side counterpart is accomplished via a new Windows Communication Foundation (WCF) service called
Client.svc, as the following illustration shows: