What is XML and why is it important?

Prior to answering these questions, the following acronyms require explanation:

HTML - HyperText Markup Language. It is the language of the Internet that tells how data should look on the screen. It is a language that "talks about" documents in terms of fonts, headings, titles etc.

SGML - Standard Generalized Markup Language. It is a metalanguage, meaning that it is a language used for defining other languages. It is incredibly powerful, but also exceedingly complex and difficult to use.

XML - eXtensible Markup Language - is a restricted form of SGML that was created specifically for the Internet.

XML was created to overcome the limitations of HTML and SGML. The limitations of HTML make it a poor tool for creating powerful and flexible information systems. It does not allow definition of custom tags for application-specific circumstances, meaning that any application created is limited in the markup tags that can be implemented to those that browser companies provide. Also, HTML is not directly reusable, meaning that translation is required when a web document needs to be changed, or when information is imported from a word processor or like application. There are other problems with HTML, but these two are the most significant for the eLearning industry.

SGML solves all these problems, but comes with the limitation of being far too complex to justify it for regular Internet implementation.

XML has the benefit of being as simple as HTML, yet with power similar to SGML. XML data is intelligent data, because it defines the meaning of the data as opposed to just the presentation (as with HTML). XML will not replace HTML, but rather complement it. HTML defines data display, and XML represents the contextual meaning of data.

For the eLearning industry, XML is a powerful tool because it allows content creators to "write once and publish everywhere." By employing XML, Gemini allows content creators to focus on creating content in the application of their choice. Further, the Gemini solution allows for easy reuse of existing content, regardless of how it was created.