There are lots of things that you can do with XML, it's a convenient way of describing data and can be happily stored in files or database fields. With something so convenient to use as you'd expect, there's been a lot of development on what's possible with XML, let's take a look...
So you've come across XML before, it stands for eXtensible Markup Language and as you'd expect means that it shares a family with other markup languages like HTML etc.. meaning that it merely decorates data, describing the strucutre that it lives in. XML can be an incredibly useful way to store information in that there are many freely available XML serialisers for classes/objects that are full of data and it can be easily written to a file or database field for later consumption.
Stands for eXtensible Stylesheet Language and these documents describe how to display documents in XML format so that they make sense to the end user. Documents produced in this way can show as documents, letters, tables etc.. whatever is required at the time. XSL works in a similar way as CSS
This stands for XSL Transformations, this is the process of taking some XML and transforming it using an XSL document into another XML document or another format like HTML - which can be very useful..