The nature of dark matter (DM) is one of the most puzzling open problems of cosmology and particle physics. Succesfull structure formation requires the thermal velocity of the DM particles to be small, i.e., the DM to be “cold” or “warm”, albeit a subdominant “hot” component could be present.
Several candidates for the role of dark matter have been proposed: among them sterile neutrinos, axions (and axion-like particles) and majorons. These candidates could costitute the dominant cold/warm DM or provide a small hot component, in different regions of the respective parameter spaces. In my talk I will review present constraints on these candidates, also in light of the recent observations of the Planck satellite.