Al-Razi, also known as Rhazes, was a prominent Persian physician and philosopher who lived during the Islamic Golden Age, around 865 to 925 CE. He is best known for his contributions to medicine, particularly in the field of pediatrics and ophthalmology. Al-Razi was one of the first to differentiate between smallpox and measles, significantly advancing the understanding of infectious diseases. In addition to his medical work, Al-Razi was a prolific writer, authoring over 200 books and treatises. His most famous work, the Kitab al-Hawi, is an extensive medical encyclopedia that compiled knowledge from various sources. Al-Razi's emphasis on observation and experimentation laid the groundwork for modern scientific methods in medicine.