Auguste Comte is generally considered to be the man who created sociology as a distinct academic discipline. Thus, his contribution to sociology is that he, in a sense, created the entire discipline.
Comte was born in 1798 in France. When he was a young adult, he was interested in the causes and the impacts of the French Revolution. He came to study the general ideas of how social order is accomplished and how societies change. Comte believed in positivism. That is, he believed that the scientific method could be used to investigate these questions even though they were about human society and not about any more physical phenomenon. Comte actually first called his field of study “social physics” because he believed that it was so similar to the hard sciences as to warrant such a name.
Much of what Comte believed is no longer believed by modern sociologists. However, the basic ideas that he was studying are still the core of modern sociology. By asking how societies maintain order and stability on the one hand, and why they sometimes change on the other hand Comte pioneered the discipline of sociology.