While developing applications in .NET Framework, we will encounter several scenarios where we need to call external APIs to get the required data. .NET Framework provides a System.Net namespace that provides a large number of helper classes that allow us to execute these operations. 

In this section, we will go through an example in which we will use the WebRequest and WebResponse classes to call the external APIs and process their responses. We will be calling an external page, and we also process the response that we will get from the call. We will also be looking at code examples in which we will learn how to make asynchronous calls to an external web server.