Can be run on four stages from the dispatcher: Before the router with %runPreRoutingFilters()% to modify parsed request data to be able to select different routers. After the router has run, but before the controller has been selected with %runRequestFilters()% (example: password protecting parts of the site). After the controller/action has run, but before the view is applied with %runResultFilters()% (example: adding common variables to be used in views, such as INI settings). After the view has run, but before the request writer writes output with %runResponseFilters()% (example: gzipping HTTP content on the fly).