The Need for XML

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The first question that needs to be addressed is why XML is even necessary when HTML is already available. Any technology that is used globally by millions and millions of people must be doing something right. As a general-purpose technology, traditional HTML meets an extraordinarily broad set of user needs. However, it doesn't fit very well with applications that rely upon specialized information, either as data files or as complex, structured documents. This is particularly true for applications such as automated data interchange, which require data to be structured in a consistent and well- formed manner.

As you have seen already, by itself, HTML just can't realistically accommodate the structuring and formatting needs of documents that require more than paragraphs, sections, and lists. HTML can't deal with more complex, application-specific problems because its elements are fixed. The language contains no provision for extending itself; namely, it has no provision for defining new elements. Although browser vendors used to add new elements all the time, any proposed extension now entails lengthy advocacy before the W3C.

Regardless, adding more element types to HTML doesn't make sense at this point. The language is already large enough. It is meant to be a general-purpose language that is capable of handling a large variety of documents. Thus, HTML needs some mechanism so that its general-purpose framework can be augmented to accommodate specialized content. It also needs to be cleaned up syntactically so that the structure of documents can be ensured. Lastly, it needs to continue to move away from a presentation style language and focus on structure. Even with modifications, traditional HTML just isn't capable of these diverse requirements, thus the need for XML.

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