In this talk I'll discuss axion cosmology and highlight peculiarities of axions as Dark Matter. Phase-space distribution of axions in the Galaxy will be considered in detail. Special attention will be given to possible observational implications of dense small-scale clumps (aka miniclusters) forming in the axionic dark matter at the QCD epoch. In particular, it is tempting to speculate that collapses of Bose-stars, which condense in miniclustrs, may explain mysterious phenomenon of cosmological Fast Radio Bursts, while tidal disruption of miniclusters is important for direct axion searches and may lead to reformulation of a search strategy.
