Description Markup Example
newline \\
exponent ^ $$x^2$$
union \cup $$\cup$$
intersection \cap $$\cap$$
space ~
tilde ‘\sim’ $$\sim$$
tilde ~ outside of TeX ~
backslash \backslash  \
x over y (division) x \over y $$x \over y$$

My list focuses on things that work in mathematical formulae without using a package, because that’s where I use TeX – for math expressions.

Other web pages:

• Handy LaTeX math reference
• Render LaTeX but copy/paste will paste only a black rectangle. Does an unattractive job on my complex example.
• Render LaTeX VERY SLOW - copy/paste of simple stuff as text works, but copy of image does not. Renders my complex example well.
• Render LaTeX - Chrome plugin. Renders well

For the copy/paste problem, you can work around it by saving the image to disk, opening with Paint, and copying from Paint.

Equation that is tough to render well:

 X(u) = \sum_{n=0}^{N-1} x(n)e^{-i2\pi un/N}

$$X(u) = \sum_{n=0}^{N-1} x(n)e^{-i2\pi un/N}$$