Understanding ghosting, unghosting, site pages and application pages

Question

well I know definations of these terms as mentioned:

Ghosted pages: Pages which are on file system and not on content db.

Unghosted pages : pages which are on content db.

Application Pages : normal asp.Net pages stored on file system.

site pages : Normal content pages stored in db.

According to these definations Site pages should always be Unghosted and Application pages should always be Ghosted.

Now here comes the problem: SP virtual path provider: provides virtual path for both ghosted and unghosted site pages. How site pages be ghosted? This msdn link(http://blogs.msdn.com/b/steve_fox/archive/2010/03/08/ghosting-unghosting-in-sharepoint-2010.aspx) also talk about ghosting and unghosting of site pages.

Could some one please explain to me these things.

Answer 1

The Ghosting/Un-Ghosting (or if you prefer the new Term Customized/Un-Customized) makes a real difference when you consider _layouts page, wcf services, etc. in the context of the SP Virtual Path provider (which then loads the Page Parser)

Example - A Document Workspace has a default.aspx (physical) where as Team Site in SP 2010 has a Wiki Page (database). Therefore Site Pages can also be physical, until you customize any of them - via SPD.

I found the best explanations here http://msdn.microsoft.com/en-us/library/bb892189(v=office.12).aspx#WSS3Inside_Integration and http://sharepointjha.wordpress.com/2011/05/16/virtual-path-provider-in-sharepoint/ and http://sharepoint.infoyen.com/2012/03/21/site-pages-vs-application-pages/