We started this part of the book with a chapter on Web Forms to set a foundation for diving into the detail of how ASP.NET Framework handles requests. In this chapter, we start our exploration of how the ASP.NET Framework defines lifecycles for web applications and the requests that it receives. An event is a message that is sent to some part of our application to indicate that something important has happened. ASP.NET defines a wide range of events to signal progress through the different lifecycle stages—we explain each of these events and show you how to use them to perform actions at key moments and take control over how your application behaves. We also introduce the key ASP.NET Framework context objects that provide the information and features that you need to respond to the lifecycle events in a meaningful manner.