This article provides ASP.NET developers with an insight into SharePoint development concepts from an ASP.NET developer’s perspective, making it easier to transition to become a SharePoint dev.

As a prerequisite, you should have a basic understanding of the differences between the SharePoint and ASP.NET platforms. These differences are explained well in SharePoint 2010: Developer Platform White Paper, and you might want to read and understand this before continuing.

http://msdn.microsoft.com/en-us/library/ff829215.aspx