While a well-formed document is well-formed because it follows rules defined by the XML spec, a valid document is valid because it matches its document type definition (DTD). The DTD is the grammar ...

Nearly everyone is talking about XML (Extensible Markup Language) these days. But few understand what it's really all about. XML's proponents claim it will cure everything that's wrong with HTML and ...

Sharing information is what the information age is all about – but sharing isn’t often simple. Electronic links with partners, customers and suppliers demand ways of defining information so ...

SGML (standard generalized markup language) is a standard for how to specify a document markup language or tag set. Such a specification is itself a document type definition (DTD). SGML is not in ...

Hypertext Markup Language (HTML) was the markup language used in a web browser; therefore, it started to be used widely.