On 24 November 1859 Charles Darwin's On the Origin of Species by Means of Natural Selection (commonly shortened to On the Origin of Species) was published in London by John Murray. The work synthesized observations from Darwin's voyages, especially the Beagle voyage (1831–1836), experiments, and correspondence with other naturalists to argue that species are not fixed but change over time through the process of natural selection. Darwin framed his argument around variation among individuals, the struggle for existence, and differential reproductive success leading to the accumulation of favourable traits. Darwin did not coin the term "evolution," which was in use by other writers, but his mechanism—natural selection—offered a testable explanation grounded in variation and inheritance. The book marshalled examples from domestic breeding, biogeography, comparative anatomy, embryology, and the fossil record. Darwin acknowledged gaps in the fossil record and the lack of a known mechanism of heredity (Mendel's work was then obscure), but he argued that the weight of diverse evidence supported descent with modification. The immediate reception combined scientific interest with theological and cultural controversy. Many naturalists engaged seriously with Darwin's evidence and responded with critiques, extensions, or alternative hypotheses. Some religious figures and lay readers perceived the implications as challenging to traditional readings of creation; others sought reconciliation between evolutionary theory and faith. Over subsequent decades, paleontology, genetics, and comparative biology furnished new evidence and refinements that strengthened and modified Darwin's original propositions. On the Origin of Species appeared after a long gestation period: Darwin had been developing his ideas for decades and began widely sharing them in letters and unpublished essays. The trigger for rapid publication was Alfred Russel Wallace's independent formulation of a similar theory of natural selection in 1858; Wallace sent Darwin a paper outlining his conclusions, prompting Darwin and his allies to present both men's work at a joint communication to the Linnean Society in July 1858 and to prepare a fuller statement for the public. Darwin's book was written in accessible prose and aimed at a broad educated readership as well as specialists. The book's impact on biological science was profound. It reoriented classification toward common ancestry, influenced research programs in morphology, embryology, and paleontology, and—after the integration of Mendelian genetics in the early 20th century—became central to the modern synthesis of evolutionary biology. Historians and scientists note that Darwin's patient accumulation of evidence and his methodological emphasis on naturalistic explanation marked a turning point in how natural history was practiced and communicated. Scholars continue to study Darwin's work in its historical context, examining his methods, the reception history across different countries and communities, and subsequent scientific developments that addressed questions Darwin himself acknowledged as unresolved. While sometimes overstated in popular accounts, the publication of On the Origin of Species remains a milestone: it presented a coherent scientific theory for biological change and set the agenda for generations of research into life's diversity.