Charles Darwin is renowned for his theory of evolution by natural selection. His groundbreaking work, published in "On the Origin of Species" in 1859, proposed that species evolve over time through a process where individuals with advantageous traits are more likely to survive and reproduce. This mechanism explains the adaptation of species to their environments and the diversity of life on Earth. Darwin's ideas challenged contemporary beliefs about creation and sparked debates in scientific, religious, and philosophical circles. His theory laid the foundation for modern evolutionary biology, profoundly influencing our understanding of life and its origins.