Kepler Telescope is a space telescope launched in 2009, monitoring the brightness of 145,000 Main Sequence Stars (or 190,000 according to another report). It is a Schmidt Camera with a 1.4 meter Primary Mirror and 95 Megapixel CCD. It is designed specifically to locate Extra Solar Planets by monitoring for Transients suggesting Transiting Planets. The original operation was continuous monitoring of a 116 square-degree field centered on Right Ascension 19h22'40", Declination +44°30'00".
Kepler has found 5,000 candidates in need of further confirmation, and past experience suggests 90% of such candidates are eventually confirmed to be exoplanets, others being attributable to star spots or Binary Stars. Over 2012-2014, 950+ Kepler-candidates have been confirmed as planets, and some other projects to find planet candidates have been curtailed or abandoned.
A failure in May 2013 (a reaction wheel failure) compromised Kepler's precision, bringing its primary mission to a close, though with many planet-candidates to be checked, more discoveries will be announced. New methods of spacecraft handling and planet hunting requiring less precision have been devised, and a "second mission", named K2 is in development.
The Kepler Dichotomy is an observed trend in the data collected from Kepler: the count of systems showing one planet doesn't seem to fit in with the counts of those showing more planets. This has led to theories holding that some systems generate and evolve planets in a manner likely to result in a single planet and others use a mechanism likely to result in two or more.
KOI stands for Kepler Object Of Interest, the term for a possible planet, i.e., the location of observations that appear to reveal a transiting planet.
California-Kepler Survey (CKS)
Extra Solar Planet