AUX - LaTeX Auxiliary File is a file extension that was created by both Latex and Tex. They are also typesetting standards in which you can depend on. You will also be able to come up with much different type of academic papers and other documentation. Footnotes, and even cross references are available with this file extension. They are available for everyone to actually use. There is also an AUX file that is used to store and cite information between different runs of the entire process. You should remember that an AUX file is also written only when a .TEX file is typeset. You will be able to greatly make use of this extension if you are familiar with tex files.