Siamese twins, also known as conjoined twins, are two individuals who are physically connected at birth. This rare condition occurs when a single fertilized egg partially separates during early development, leading to twins who share certain body parts or organs. The degree of connection can vary widely, from sharing a small area to being joined at vital organs. The term "Siamese twins" originated from the famous conjoined twins Chang and Eng Bunker, who were born in Siam (now Thailand) in 1811. They became well-known in the 19th century and lived a full life, even marrying and having children. Today, medical advancements allow for better understanding and potential surgical separation of conjoined twins when feasible.