1. What is XML used for?
XML is used for structuring data. It could be compared to a set of guidelines or rules for creating text formats that are then used to structure data. Structured data includes address books, configuration parameters, financial transactions, spreadsheets, technical drawings, etc. XML enables you to generate and read data, as well as make sure that the data structure is unmistakable.
2. XML resembles (only resembles) HTML
Both XML and HTML use tags and attributes. However, here is the difference: HTML describes what a tag or attribute means and what the text will look like in a browser. The only thing XML does is delimit pieces of data. Each application that reads that data will interpret it depending on the context.
3. XML files are text files but you shouldn’t have to read them
All XML files are in a simple text format. They are not, however, meant to be read unless it is necessary. And when it becomes necessary, it brings several benefits. Since it is text, you do not need to use the same program that was used to create it to be able to view it. Any text editor will do the trick. This makes it easier to debug applications. If an XML file is broken, an application reading it cannot second-guess the interpretation. It automatically stops and reports an error.
4. XML is wordy
XML files are larger than binary formats. This is due to them being a text format and using tags to delimit data. However, the advantages of a text format outweigh this disadvantage as large files can be quickly and easily compressed.
5. XML belongs to a family of modules
XML belongs to a family of technologies that accomplish highly demanded and important tasks. For example:
- XLink is used to describe a standard way to hyperlinks to an XML file.
- XPointer is used to point to pieces of data inside an XML file.
- XSLT is used to add, delete, and rearrange tags and attributes.
- SL is used for expressing style sheets.
- DOM is used for manipulating XML files from a programming language.
- XML Schemas are used for defining precisely the structures of XML-based formats.
6. XML is not as new as you might think
XML first underwent development in 1996 and W3C started recommending it in February 1998. However, XML technology is based on SGML developed in the early 1980s. After having worked with HTML (developed in 1990) for a few years, the creators of XML used that experience to pick the best bits of SGML and create something equally powerful but significantly easier. There are big differences between SGML and XML but the technology they are based on is the same.
7. XML + HTML = XHTML
XHTML is the successor of HTML. It mirrors or extends versions of HTML. It comes with many of the same elements. However, the syntax underwent some changes to comply with the rules of XML. An XML-based format assumes the syntax from XML but restricts it in certain ways and adds meaning to it. XHTML is an application of XML and a more restrictive subset of SGML.
8. XML is adjustable
With XML you can reuse and combine other formats to define a new document format. However, you must remember that each format is developed independently, which means that elements or attributes with the same may have different meanings. XML provides a namespace mechanism that allows you to eliminate name confusion. Some XML-based formats that use namespaces are XSL and RDF.
9. RDF and Semantic Web are based on XML
RDF (Resource Description Framework) is a framework used for describing resources on the web. For example, it is used to describe properties like price and availability for shopping items, time schedules for web events, information such as author, content, create date, etc. about web pages, content and rating for web pictures, content for search engines, and electronic libraries. RDF is written in XML, which allows the information to be easily exchanged between different types of computers using different operating systems and application languages. RDF is part of the W3C’s Semantic Web Activity. It uses Web identifiers to identify resources and describes them with properties and property values.
10. XML is license-free, platform-independent, and very well-supported
Using XML means that you need to create your own database, programs, and procedure that manipulate it. There are, however, many tools available that make it much easier. There is also an ever-growing community of people who have already gained a lot of experience and can help you. XML is also license-free, so you don’t have to pay for it and you can create your own software around it. No specific platform is needed to read XML files. All that’s needed is a parser.