Historically, the World Wide Web has not provided a simple means for presenting math content online. Mathematicians and scientists typically use software such as TeX  and LaTeX  for typesetting complex formulas and then convert these formulas to images for presentation online. Presenting formulas using images creates accessibility challenges for individuals with visual impairments because they typically don't scale well when enlarged, and because they can't be communicated orally without considerable extra effort from the author to add alternate text to each image. Adding alternate text to images of mathematical notation is complicated by the need to communicate in a standard language such as MathSpeak  in order to avoid ambiguity.
In October 2003, the World Wide Web Consortium (W3C)  published its formal recommendation for support for Mathematical Markup Language (MathML), an Extensible Markup Language (XML) application for describing mathematical notation in a way that preserves both structure and content. It allows formulas to be rendered in meaningful ways by audible screen readers and other access technologies. The use of MathML has increased extensively in recent years. As a result, making online math content accessible to students who are blind is now attainable.
The W3C maintains a list of software that supports MathML, including editors, calculators, composition and rendering engines, converters, authoring systems, browsers and browser plug-ins, and more. For details see the W3C MathML Implementations Page .
For additional information on MathML, consult the Knowledge Base article What is MathML? 
-  TeX
-  LaTeX
-  MathSpeak
-  World Wide Web Consortium (W3C)
-  W3C MathML Implementations Page
-  What is MathML?