  The physics of axions and axion-like particles (ALPs) is enjoying an
incredibly productive period, with many new experimental proposals, theoretical
idea, and original astrophysical and cosmological arguments which help the
search effort. The large number of experimental proposals is likely to lead to
fundamental advances (perhaps, a discovery?) in the coming years. The aim of
this article is to provide a very brief overview of some of the recent
developments in axions and ALP phenomenology, and to discuss some relevant
aspects in this important field. A particular attention is given to the
definition of motivated regions in the axion parameters space, which should be
the targets of experimental searches.
