Clinical development refers to the process of researching, testing and developing new drugs or therapies through human clinical trials. This involves a series of steps that take place over many years to ensure that the drug is safe and effective for humans before it can be approved for use in medical practice. The goal of clinical development is to gather data on the drug's safety, efficacy, and optimal dosage through various stages of testing, including Phase I (safety), II (efficacy) and III (comparison with existing treatments). This process ensures that any potential risks or side effects are identified before the drug is made available to patients.