@Page

The @Page directive defines page-specific attributes used by the ASP.NET page parser and compiler. An example of a @Page attribute is Language, which specifies the default language for the page.

@Control

The @Control directive defines control-specific attributes used by the ASP.NET page parser and compiler. An example of a @Control attribute is Description, which provides a text description of the control.

@Import

The @Import directive explicitly imports a namespace into a page. The only attribute supported by the @Import directive is Namespace, which indicates the name of namespace to import.

@Register

The @Register directive associates aliases with namespaces and class names for concise notation in custom server control syntax.

@Assembly

An assembly is a unit of reusable code compiled into a .dll file. The @Assembly directive links an assembly against the current page, making all of the assembly’s classes and interfaces available for use on the page. The only attribute supported by the @Assembly directive is Assemblyname, which indicates the name of the assembly to link. Assemblies that reside in an application \bin directory are automatically
linked to pages within the application, therefore, they do not need to be linked using the @Assembly directive.

@OutputCache

The @OutputCache directive controls the output caching policy for the page. An example of a @OutputCache attribute is Duration, which specifies the time (in seconds) that the output cache for the page will be maintained.