Darwin's theory of evolution explains how species change over time through a process called natural selection. This theory suggests that individuals with traits better suited to their environment are more likely to survive and reproduce. Over generations, these advantageous traits become more common in the population, leading to gradual changes in the species. The theory is based on observations made by Charles Darwin during his voyage on the HMS Beagle. He studied various species, particularly on the Galápagos Islands, and noted how they adapted to their specific environments. This foundational idea has greatly influenced our understanding of biology and the diversity of life on Earth.