Charles Darwin was an English naturalist whose book, 'On the Origin of Species,' introduced the scientific theory that populations evolve over generations through a process of natural selection. His ideas were primarily shaped by his five-year voyage on the HMS Beagle, during which he observed the unique flora and fauna of the Galápagos Islands. Darwin proposed that all species of life have descended over time from common ancestors. This 'descent with modification' challenged the prevailing religious and scientific views of the Victorian era regarding the creation of the world. While controversial at the time, his work provided a unifying logic for the life sciences. Darwin was a meticulous researcher, spending 20 years gathering evidence before publishing his findings. Today, evolution by natural selection is the foundational principle of modern biology, and Darwin's legacy continues to influence genetics, ecology, and our understanding of humanity's place in nature.