Extensible Application Markup Language (XAML) is a declarative markup language used to create user interfaces. There are two types of XAML control frameworks available in Sitecore, XML control and xamlControls. In this recipe, we will create the Sheer UI application using XML control and, based on this, you will be able to create an application using xamlControls as well. You can get some basic information about both from https://goo.gl/4WWeVw.
Sitecore has built a new framework, SPEAK, which is a replacement for the XAML/Sheer UI, so we will not focus much on it. However, it's good to know how it works so that it can be helpful in customizing existing applications. Here, we will create an application to list all products as well as delete selected products. You will learn how to use different controls, invoke methods, handle messages, and create events in XML control.