  In 1980, Leedham-Green and Newman introduced the invariant coclass to the
theory of groups of prime-power order and they proposed five far-reaching
conjectures related to it. Their work has initiated a deep and fruitful
research project in group theory that is still ongoing today. We outline the
main results of this celebrated article, we describe the history leading to it,
and we survey some highlights of work inspired by these results.
