The XML 1.0 Recommendation (published in February 1998) was the first step towards the next generation Web, allowing each community to design languages that suit their particular needs and integrate them harmoniously into a general infrastructure based on XML.
Chemical ML February 1998 – first XML DTD to be published.
SMIL allows authors to create synchronized multimedia presentations on the Web.
DOM: The Document Object Model is an application programming interface for providing access to document structure, style, events, and more. Because it does not rely on a particular programming language, it facilitates the design of active Web pages and provides a standard interface for other software to manipulate HTML and XML documents. DOM Level 1 was published in October 1998 followed, in November 2000, by DOM Level 2.
RDF: The Resource Description Framework Model and Syntax specification (published in February 1999) is the first Recommendation on which the Semantic Web will be built. RDF provides a standard vocabulary and encoding techniques to attach metadata to any resource on the Web.
MathML 2.0: MathML 2.0, published in February 2001 (based on an earlier release published in July 1999), is the fundamental tool for marking up mathematics on the Web using XML.