Recording Changes (changes.sty)
\documentclass[12pt]{article}
\usepackage{changes}
\definechangesauthor[name={Mabel Canary},color=violet]{MC}
\definechangesauthor[name={Fred Canary},color=blue]{FC}
\definechangesauthor[name={Prof Important Person},color=teal]{IP}
\begin{document}
\section{About the Lab}
The Secret Lab of Experimental Stuff is a
\replaced[id=MC]{top-secret}{sinister} laboratory
whose existence is highly classified so don't tell
anyone about it\added[id=FC]{ or we'll get really cross with you}.
The \added[id=IP]{world-renown} University of Somewhere denies all
knowledge of the Secret Lab of Experimental Stuff, except on Open
Days where members of the public may visit the facility and ask
questions as long as they consent to a memory wipe when they leave.
The memory wipe is \deleted[id=MC,remark={no it isn't}]{completely}
harmless and your memory of the visit will be replaced by a
\added[id=MC]{pleasant} recollection of spending the day feeding the
\replaced[id=FC,remark={what geese?}]{ducks}{geese}
\added[id=MC,remark={they're the weird-looking ducks}]{and geese} in
the nearby pond.
\end{document}
Download changes-sample.tex or changes-sample.pdf.