The achievement that Charles Darwin is most known for is his development of the theory of evolution, particularly in his book "On the Origin of Species." In the book, Darwin collects evidence and crafts arguments showing that living things change over time and have genetic relation to one another.
While Darwin was writing "On the Origin of Species," Charles Lyell read a paper with similar ideas by Alfred Russel Wallace. He encouraged Darwin to publish his paper first, who then decided to write a short paper, but during the writing process, he changed his mind and expanded to a book about species. After Wallace wrote his own paper about natural selection, a joint presentation was scheduled. It didn't make a significant impact in the scientific community.
Darwin's "On the Origin of Species" was released in 1859, and it was surprisingly successful. The book was somewhat controversial, attracting criticism as well as ardent followers. This lead to the Darwinism movement, which covered various evolutionary ideas. "On the Origin of Species" became an important scientific book, available in many different languages.
Darwin's reputation in the scientific community is that of an excellent scientist with revolutionary ideas. His theory of evolution is widely considered to be accurate, with his concept of natural selection as the basis of evolution.