User blog comment:Primussupremus/Ultrabillion/@comment-28606698-20170314140146/@comment-28606698-20170314190637

Yes you should know fast-growing hierarchy, especially since it has simple definition. In googology fast-growing hierarchy is universal benchmark for comparison of strength of different notations. It is simpler to understand a notation if you know its limit in terms of fast-growing hierarchy, for example omega for Knut's arrow notation, omega^2 for Conway's chain notation, omega^omega for Bowers's linear array notation