Before 1992 astronomers thought that planets had only formed in our solar system. Thanks to our increasingly advanced observation and detection methods, new exoplanets are discovered almost every day. As of 20 May 2014, we have knowledge of 1792 planets in 1112 planetary systems, including 460 multiple planetary systems. There are billions of planets in our Milky Way and only a fraction have so far been observed.
The information-graphic below presents the kinds of exoplanets found so far and the detecting methods used. It also indicates those few which have the potential to inhabit liquid water. The most recent planet found with a potential for holding life is Kepler-186-f.