  We present an overview of recent developments in the detection of light
bosonic dark matter, including axion, pseudoscalar axion-like and scalar dark
matter, which form either a coherently oscillating classical field or
topological defects (solitons). We emphasise new high-precision laboratory and
astrophysical measurements, in which the sought effects are linear in the
underlying interaction strength between dark matter and ordinary matter, in
contrast to traditional detection schemes for dark matter, where the effects
are quadratic or higher order in the underlying interaction parameters and are
extremely small. New terrestrial experiments include measurements with atomic
clocks, spectroscopy, atomic and solid-state magnetometry, torsion pendula,
ultracold neutrons, and laser interferometry. New astrophysical observations
include pulsar timing, cosmic radiation lensing, Big Bang nucleosynthesis and
cosmic microwave background measurements. We also discuss various recently
proposed mechanisms for the induction of slow `drifts', oscillating variations
and transient-in-time variations of the fundamental constants of Nature by dark
matter, which offer a more natural means of producing a cosmological evolution
of the fundamental constants compared with traditional dark energy-type
theories, which invoke a (nearly) massless underlying field. Thus, measurements
of variation of the fundamental constants gives us a new tool in dark matter
searches.
