Biological samples are materials taken from living organisms for scientific analysis. These samples can include blood, saliva, tissue, or even urine. Researchers use these samples to study health, diseases, and the effects of treatments. For example, a doctor might collect a blood sample to check for infections or monitor a patient's health. In addition to medical research, biological samples are also important in fields like forensic science and environmental studies. Forensic scientists analyze samples from crime scenes to identify suspects, while environmental scientists study samples from soil or water to assess pollution levels. These analyses help us understand and improve our world.