This paper discusses MathML, an XML-based standard for expressing mathematics - everything from elementary mathematics to undergraduate college-level mathematics. Limitations of pre-existing options led to the creation of MathML. MathML is designed to be useful for authoring and publishing, for creating online interactive math resources, and as a non-proprietary approach for archiving. MathML is supported by the W3C and by multiple scholarly publishers and vendors of computer-based mathematics software. The question now is whether MathML can achieve greater acceptance among authors and better integration with standards in related domains, either through cross-walks or through direct incorporation into other domain schemas.