A Kepler object of interest (KOI) is a star observed by the Kepler space telescope that is suspected of hosting one or more transiting planets. KOIs come from a master list of 150,000 stars, which itself is generated from the Kepler Input Catalog (KIC). A KOI shows a periodic dimming, indicative of an unseen planet passing between the star and Earth, eclipsing part of the star. However, such an observed dimming is not a guarantee of a transiting planet, because other astronomical objects—such as an eclipsing binary in the background—can mimic a transit signal. For this reason, the majority of KOIs are as yet not confirmed transiting planet systems.
The Kepler mission lasted for 4 years from 2009 to 2013.[1] The K2 mission continued the mission for next 5 years and ended in October 2018.[2] The KOI provides a catalogue of 10,000 astronomical bodies[3] and many of those have been confirmed as exoplanets. The KOI numbers are not going to increase and with advanced technology telescopes, KOIs could become confirmed exoplanets faster than before.[4]