$J/\psi$ production and interactions with the medium

$J/\psi$ production provides a sensitive probe of the properties of the hot and dense medium created in high energy heavy ion collisions at RHIC. $J/\psi$ suppression due to Debye screening was long considered to be a leading signature of Quark Gluon Plasma formation. Recent theoretical studies suggest that such suppression can be compensated by recombination, or explain suppression by decreased feed-dowm from "melted" higher mass quarkonia, while $J/\psi$'s themselves remain unscreened. Measurement of $J/\psi$ production in nucleus-nucleus collisions at RHIC can clarify these questions. Baseline measurements in pp and dAu collisions can be used to distinguish cold nuclear matter effects. In this talk I will review recent results in this field from the PHENIX Experiment.