A drug target is a molecule in the body, usually a protein, that is intrinsically associated with a particular disease process and that could be addressed by a drug to produce a desired therapeutic effect.An effective drug target comprises a biochemical system rather than a single molecule. Present target definitions are static. We know this to be insufficient, but techniques to observe the dynamics of drug–target interactions are just being created. Most importantly, we are not able to gauge the interaction of the biochemical “ripples” that follow the drug’s initial molecular effect. The first molecular step of drug activity consists in mass-action governed drug–target recognition. For clinically observable activity, a series of biochemical steps need to follow that have to shift physiological equilibria in a transient way. Indeed, the gap between chain and circles of molecular events and clinical effects is still wide open, as reflected by the complementarity of target and phenotypic-oriented drug discovery approaches