Developed at Wolfram Research over nearly 20 years, Mathematica has by far the world's most sophisticated and convenient mathematical typesetting technology. Generalizing the concept of a computer language to allow 2D input, Mathematica allows both interactive and programmatic entry of arbitrarily complex typeset expressions, with publication-quality layout continuously maintained in real time.
StandardForm — Mathematica unambiguous format (Ctrl+Shift+N)
TraditionalForm — traditional textbook math notation (Ctrl+Shift+T)
InputForm — linear input form (Ctrl+Shift+I)
Palettes ► Other ► Basic Math Input — bring up a palette of common input notations
Palettes ► Special Characters — access all Mathematica special characters »
(EscpEsc) ▪ (EsciiEsc) ▪ ∞ (EscinfEsc) ▪ (EscintEsc) ▪ (differential d) (EscddEsc) ▪ (EscaEsc) ▪ ...
Text — text within math
HoldForm — display expressions without evaluating them