What is the concept of virtual path provider?

Any project has two parts one is the standard and common part and the other is the customized version. In ASP.NET we have two types of pages for any project one is common ASPX pages and the other is customized ASPX pages. Common pages are stored on file directories while customized versions of pages are stored in content database.

So in other words we need an abstract mechanism by which we can render pages from SQL Server content database and also from the virtual directories. This is achieved by using the virtual provider provided by SharePoint. So for all customized pages virtual provider reads from the content database and passes the same to the ASP.NET runtimes. For all common pages it goes to the directory, parses it and the passes the same across to the ASP.NET runtime.
 

Virtual provider is an abstraction which loads the page from the content or the file system depending on whether it’s customized or common pages and passes the same to the ASP.NET runtime.