Élie Metchnikoff (also known as Ilya Ilyich Mechnikov), born on May 16, 1845, in Kharkov, Russian Empire (now Ukraine), was a distinguished microbiologist and a pioneering researcher in the field of immunology. After earning his degree in natural sciences from the University of Kharkov, Metchnikoff went on to work in various academic and research institutions across Europe. His most significant discovery was the concept of phagocytosis, the process by which certain white blood cells protect the body by ingesting harmful foreign particles, bacteria, and dead or dying cells, a discovery that won him the Nobel Prize in Physiology or Medicine in 1908 alongside Paul Ehrlich. Metchnikoff's research profoundly influenced the understanding of the immune system and laid the groundwork for modern immunology. Additionally, Metchnikoff had a keen interest in the process of aging and longevity. His book, 'The Prolongation of Life: Optimistic Studies' (1908), explores his theories on aging and how it might be influenced by factors such as diet and lifestyle. He advocated for the importance of beneficial gut microbiota and the consumption of fermented foods, ideas that prefigured probiotics' role in health. His inquiries into longevity, coupled with his scientific investigation into immunology, mark him as a visionary thinker whose work continues to have a significant impact on medical science. Metchnikoff passed away on July 15, 1916, but his legacy endures.