  The number of exoplanets detected using gravitational microlensing technique
is currently larger than 200, which enables population studies. Microlensing is
uniquely sensitive to low-mass planets orbiting at separations of several
astronomical units, a parameter space that is not accessible to other
planet-detection techniques, as well as free-floating planets, not orbiting
around any star. In this review, we present the state-of-the-art knowledge on
the demographics of exoplanets detected with microlensing, with a particular
emphasis on their occurrence rates. We also summarize the current knowledge
about free-floating planets, an elusive population of objects that seem to be
more common than ordinary, gravitationally bound exoplanets.
