Abstract. Since the time of Kant it
has been supposed that angular momentum (AM) was fundamental to the nature of
the `spiral nebulae', now known as galaxies. A century after the first
measurement of galaxy rotations, theoretical and observational tools are now
mature for systematic analyses of galaxy AM. This colloquium will commence by
discussing the cosmological origin of AM and its role of AM in shaping
galaxies. It will then highlight recent progress in understanding the
detailed relationship between AM and galactic substructure, highlighting
(1) the strong connection between atomic gas fraction and AM modelled
via the new parameter `q' (Obreschkow & Glazebrook 2014, 2016), (2) the
mass-AM-morphology relation, and (3) the role of AM in clumpy, turbulent
disk galaxies. Limitations of the results are discussed carefully as is
their potential to revolutionise our views on galaxy evolution in a
cosmological context.