Different between Application page and Site pages In SharePoint 2013?

Site pages should always be Unghosted and Application pages should always be Ghosted

Application Pages

Site Pages

normal asp.Net pages stored on file system SharePoint Designer tool cannot be used with application pages Application pages cannot be used within sandboxed solutions cannot be customized and modified by end user, instead a developer is required have to deploy your master page within the virtual directory or _layouts folder. they are much faster Normally application pages are not web part pages can only contain server controls or user controls and cannot be personalized by users Easiest way to deploy your existing ASP.Net web site within SharePoint is to deploy its pages as Application Pages within SharePoint

Normal content pages stored in db. then actual page is parsed at runtime and delivered to end-users Site pages can be edited by using SharePoint Designer tool Site pages are used within Sandboxed solutions. A site page can be customized and modified by end user One of the biggest catch of the SharePoint is the page layouts, where you can modify page once for a specific content type and then you can create multiple pages using the same page layout with different contents they are at user-level not at web-application or farm level and can be customized per site level If you want to add any inline code to master page, first you need to add following configuration within web.config: To add code behind to SharePoint master pages or page layouts.