The most widely accepted solution to the Strong CP problem is the QCD axion, whose traditional parameter space is relatively constrained. However, recent studies on exotic axion models have shown that this space can be significantly extended, opening up a wide range of previously unexplored possibilities for model building. In this talk, I will first review the current status of axions and axion-like particles, then focus on the challenges related to the origin of their masses and explore potential connections to other unresolved issues within the Standard Model.