XML is short for eXtensible Markup Language. It is a very widely used format for exchanging data, mainly because it's easy readable for both humans and machines. If you have ever written a website in HTML, XML will look very familiar to you, as it's basically a stricter version of HTML. XML is made up of tags, attributes and values and looks something like this:
<user name="Sandy Doe" age="28" />
<user name="Mani Doe" age="22" />
As you can see, for a data format, this is actually pretty easy to read, and because it's such a widespread standard, almost every programming language has built-in functions or classes to deal with it. C# is definitely one of them, with an entire namespace, the System.Xml namespace, to deal with pretty much any aspect of XML. In the following chapters, we will look into using them, both for writing and reading XML. Read on!