In its simplest sense, XML is a markup language that uses tags to describe elements, much like HTML. Unlike HTML, however, XML doesn't contain any predefined tags—in XML, you make up your own tags to describe your data.
Take a look at some simple XML data, as shown in Listing 27.1. (You can find this content in Jumpstart\XMLIntro\EmployeeData.xml.)
<?xml version="1.0" encoding="utf-8" ?> <!-- Employee Information -- > <EmployeeData> <Employee ID="1"> <FirstName>Davolio</FirstName> <LastName>Nancy</LastName> </Employee> <Employee ID="2"> <FirstName>Fuller</FirstName> <LastName>Andrew</LastName> </Employee> <Employee ID="3"> <FirstName>Levering</FirstName> ...