Axions and Axion-like-particles: recent progress

Bethe Colloquium - After introducing the concepts of axions and axion-like-particles (ALPs) and their phenomenology, axions which solve the strong CP problem but can be either much heavier or much lighter than the canonical QCD axion will be discussed. I will also present recent theoretical developments which can soften the ultraviolet sensitivity of ALPs and result in degenerate ALPs.