Writing mathematics with MathML
Mathematical Markup Language — or MathML — is the markup language used to write mathematical formulas in web pages using fractions, scripts, radicals, matrices, integrals, series, etc. Although it was originally designed as an independent XML language, MathML is generally embedded inside HTML documents and can be seen as an extension of HTML.
Warning: In practice, MathML content is generated from lightweight markup languages (e.g. LaTeX) or using graphical user interface: if you just need to integrate mathematical formulas in your web pages, the tips from the Authoring MathML page should be enough.
Prerequisites
Before attempting to learn MathML, it is assumed that you have some basic knowledge of HTML and CSS. Consequently, you are strongly advised to get familiar with at least these two technologies first. Start by working through the following modules:
Some familiarity with mathematical notations and TeX rendering rules might also come in handy, even though required concepts will be explained as needed.
Modules
 MathML first steps

MathML is the markup language used to write mathematical formulas in Web pages. This module provides a gentle beginning to your path towards MathML mastery with the basics of how it works, what the syntax looks like, and how you can start using it inside HTML.
See also
 MathML on MDN

The main entry point for MathML documentation on MDN, where you'll find detailed reference documentation for all features of the MathML language. Want to know all the values a property can take? This is a good place to go.