Abstract
We overview the current status of axions as dark matter. The axion is the pseudo-Nambu–Goldstone boson which arises from the Peccei–Quinn solution to the strong CP problem. Additionally, cold axion populations that can contribute to the dark matter of the universe will be generated via this mechanism. After reviewing these topics, we focus on constraints from the laboratory, astrophysics and cosmology. We discuss the current status of experimental searches and the consequences of the distribution of dark matter axions in the galactic halo for these searches. The axion remains an excellent candidate for the dark matter and future experiments, particularly the Axion Dark Matter eXperiment (ADMX), will cover a large fraction of the axion parameter space.