• An XML language to express Mathematics
• Designed for use on the Web: CSS, XLink
• Comes in two flavours: Presentation and Content

$\frac{1}{1+\frac{e^{-2\pi }}{1+\frac{e^{-4\pi }}{1+\frac{e^{-6\pi }}{1+\text{...}}}}}=(\sqrt{\frac{5+\sqrt{5}}{2}}-\frac{\sqrt{5}+1}{2})e^{2\frac{\pi }{5}}$