Élie Metchnikoff was a Russian zoologist and microbiologist born in 1845. He is best known for his pioneering work in immunology, particularly for his discovery of phagocytosis, the process by which certain cells engulf and digest harmful microorganisms. This groundbreaking research laid the foundation for understanding how the immune system protects the body from infections. In addition to his work in immunology, Metchnikoff was also interested in the role of probiotics in health. He believed that consuming beneficial bacteria could promote longevity and improve overall well-being. His ideas contributed to the development of the field of microbiology and influenced modern health practices.