In vivo screening is a method of testing potential drug candidates or therapeutic interventions in living organisms, such as animals or humans, to assess their safety, efficacy, and potential for clinical use. This method involves administering the drug or intervention to the organism and monitoring its effects on various biological processes, behaviors, or disease states. In vivo screening allows researchers to observe how the drug interacts with the body as a whole, and can provide valuable information on its pharmacokinetics, toxicity, and potential side effects. This method is crucial in drug discovery and development, as it helps researchers identify promising candidates for further study and eventual clinical trials.