The CommonHTML output processor renders your mathematics using HTML
with CSS styling. It produces high-quality output in all modern
browsers, with results that are consistent across browsers and
operating systems. This is MathJax’s primary output mode since
MathJax version 2.6. Its major advantage is its quality, consistency,
and the fact that its output is independent of the browser, operating
system, and user environment. This means you can pre-process
mathematics on a server, without needing to know the browser, what
fonts are available, and so on. (In version 2, both the
NativeMML processors produced different output for different
browsers and user environments.)
The CommonHTML output uses web-based fonts so that users don’t have to have math fonts installed on their computers, but will use locally installed ones if they are available. It currently only supports MathJax’s default TeX fonts (see the MathJax Font Support section for more information).
See CommonHTML Output Processor Options for information about the options that control the CommonHTML output.