# Differences from Actual TeX¶

Since MathJax renders for the web and TeX is a print layout engine, there are natural limitations to which parts of TeX can be supported in a reasonable way. Accordingly, there are several differences between “real” TeX/LaTeX systems and MathJax’s TeX Input.

First and foremost, the TeX input processor implements only the math-mode macros of TeX and LaTeX, not the text-mode macros. MathJax expects that you will use standard HTML tags to handle formatting the text of your page; MathJax only handles the mathematics. So, for example, MathJax does not implement \emph or \begin{enumerate}...\end{enumerate} or other text-mode macros or environments. You must use HTML to handle such formatting tasks. If you need a LaTeX-to-HTML converter, you should consider other options.

There are two exception to this rule. First, MathJax supports the \ref macro outside of math-mode. Second, MathJax supports some macros that add text within math-mode (such as \text{}) as well as $...$ and $$...$$ within such macros (to switch back into math-mode) and \\$ to escape.

Second, some features in MathJax might be necessarily limited. For example, MathJax only implements a limited subset of the array environment’s preamble; i.e., only the l, r, c, and | characters alongside : for dashed lines — everything else is ignored.