The SqlTriggerContext Object
The SqlTriggerContext class provides context information about the trigger. This contextual information includes the type of action that caused the trigger to fire, which columns were modified in an UPDATE operation, and, in the case of a data definition language (DDL) trigger, an XML EventData structure that describes the triggering operation. For more information and examples of how to use the SqlTriggerContext class, see CLR Triggers.
For more information, see the Microsoft.SqlServer.Server.SqlTriggerContext class reference documenation in the .NET Framework SDK documentation.