• What namespaces are imported by default in ASPX files?

The following namespaces are imported by default. Other namespaces must be imported manually using @ Import directives.
• System
• System.Collections
• System.Collections.Specialized
• System.Configuration
• System.Text
• System.Text.RegularExpressions
• System.Web
• System.Web.Caching
• System.Web.Security
• System.Web.SessionState
• System.Web.UI
• System.Web.UI.HtmlControls
• System.Web.UI.WebControls