Cosmas and Damian are twin brothers and early Christian martyrs known for their medical skills. They practiced medicine without charging patients, earning them the title of "unmercenary physicians." Their dedication to helping others and their faith in Christianity made them popular figures in the early church. The brothers were eventually arrested for their beliefs and faced persecution. They are celebrated as saints in various Christian traditions, particularly in the Eastern Orthodox and Roman Catholic churches. Their feast day is observed on September 26, honoring their contributions to medicine and their unwavering faith.