ActionFilterAttribute

https://msdn.microsoft.com/en-us/library/system.web.mvc.actionfilterattribute.onactionexecuting(v=vs.118).aspx#M:System.Web.Mvc.ActionFilterAttribute.OnActionExecuting(System.Web.Mvc.ActionExecutingContext)

The ASP.NET MVC framework will call the OnActionExecuting method of your action filter before it calls the action method that is marked with your action filter attribute. Similarly, the framework will call the OnActionExecuted method after the action method has finished.

Understanding Action Filters (C#)

Filters

Filtering in ASP.NET MVC