C-\ is one of my favorite Emacs keybindings :). You use it to change input methods, in my case to write e.g. Greek letters and other Unicode symbols in plaintex

C-\ is one of my favorite Emacs keybindings :). You use it to change input methods, in my case to write e.g. Greek letters and other Unicode symbols in plaintext files using TeX notation. I sometimes like to program using Unicode variable names when doing physics/math, and this is an easy way to do so built into Emacs.