XML is the abbreviation of Extensible Markup Language. This language is considered to be a huge evolution on internet. However, those who don’t program or don’t work with Web tools may not perceive XML advantages.
XML is a technical specification developed by W3C (World Wide Web Consortium, entity responsible of the graphic area on internet) to surpass HTML limitations. HTML is the standard of Web pages.
XML language is defined as an universal format for structured data on Web. These data consist of tables, pictures, configuration parameters, etc. So, the language defines rules that allow the writing of these documents, in such a way that they can be adequately visible on computers.
There are some similarities with HTML and XML. For example: both use tags. However, if a tag opened in HTML is not closed, the page stills being exhibited. But in XML, the application would stop immediately. This example shows HTML is a more tolerant language, while XML is highly rigid. This can sound as a disadvantage, but it’s compensated by XML extensibility.