XML uses tags just like HTML. XML, however, is also extensible, so it doesn't have a fixed set of tags such as HTML, which makes HTML inflexible.

With XML you can design your own markup tags.

The big winner for XML is that it adds context and gives meaning to data. However, XML uses tags only to delimit pieces of data, the custom tags help represent data logically.

The interpretation of the data is left to the application that reads it, via the DTD (Document Type Definition) or XML Schema.