  Prior to the 1990s, speculations about the occurrence of planets around other
stars were based only on planet formation theory, observations of circumstellar
disks, and the knowledge that at least one seemingly ordinary star is the host
of four terrestrial planets, two gas giants, and two ice giants. Since then,
Doppler and transit surveys have been exploring the population of planets
around other Sun-like stars, especially those with orbital periods shorter than
a few years. Over the last decade, these surveys have risen to new heights with
Doppler spectrographs with a precision better than 1 m/s precision, and space
telescopes capable of detecting the transits of Earth-sized planets. This
article is a brief introductory review of the knowledge of planet occurrence
that has been gained from these surveys.
