About
AUCTeX is an extensible package for writing and formatting TeX files in GNU Emacs. It supports many different TeX macro packages, including AMS-TeX, LaTeX, Texinfo, ConTeXt, and docTeX (dtx files).
AUCTeX includes preview-latex which makes LaTeX a tightly integrated component of your editing workflow by visualizing selected source chunks (such as single formulas or graphics) directly as images in the source buffer.
AUCTeX is available on GNU ELPA.