What is XML?

XML is a standard that gives meaning to data. XML does this in such a way that it is legible for both machines and humans. Take the piece of XML below. We understand it, but so does a computer:

Data are called 'elements' and can be found in a 'tag', like <URL>...</URL>. These elements are always placed in a certain structure, as shown in the example. This way, the computer is able to recognise the element and a program can use it. When designing element names and structure, it is important to make sure that selected data can be placed there logically and conveniently.

XML itself allows you the freedom to name your own structure, element names and other characteristics. Within the XML standard it doesn't matter whether something is called <URL> or <href>. But the software that uses XML does need to know exactly what it says. That is why you need additional standards like DTDs or schemas to lay the down unambiguously what is meant.

One XML isn't the other. It often occurs that a message received in one XML structure has to be transformed to another. There are specialised transformation languages for this, such as XSLT and XQuery.

XML can be found everywhere by now and is used for data storage, websites, communication, reporting, and much more. Did you know that even your digital camera records the picture data - the metadata - in XML?

Unfortunately, a good application of XML is often more difficult than expected. Xatapult is happy to assist you.