Communicable diseases are illnesses that can be transmitted from one person to another, often through direct contact, airborne particles, or contaminated surfaces. Examples include influenza, tuberculosis, and COVID-19. These diseases can spread quickly, especially in crowded or unsanitary conditions. Preventing communicable diseases involves practices like regular handwashing, vaccination, and maintaining good hygiene. Public health measures, such as quarantine and contact tracing, are also important in controlling outbreaks. Understanding how these diseases spread helps individuals and communities protect themselves and reduce transmission rates.