An in vivo study is a scientific investigation conducted within a living organism, such as a human or animal, to observe the effects of a substance or treatment. This type of study allows researchers to closely mimic real-life conditions and gather valuable data on how a substance or treatment interacts with the body. In contrast to in vitro studies, which are conducted in a controlled laboratory setting, in vivo studies provide a more comprehensive understanding of how a substance or treatment may function in a living system. These studies are crucial in the development of new medicines and treatments, as they provide valuable insights into the safety and efficacy of potential treatments.