There are four major ways in which researchers are hunting for planets. Technically, these are called astrometry, spectroscopy, interferometry, and photometry. For descriptive purposes, however, I refer to them respectively as the wobble method, the speed-trap technique, the zebra-stripe procedure, and the shadow approach.
The Quest for Alien Planets: Exploring Worlds outside the Solar System, Chapter I (p. 16), Plenun Trade. 1997