Sherlock Holmes is a recurring character in a series of stories and novels by 19th century British author Arthur Conan Doyle. He is a type of character known as an "amateur detective", a type one finds in many types of mystery or detective novels. The genre of amateur detective originated in the mid-19th century with such characters as Robert Audley in Lady Audley's Secret and Poe's Auguste Dupin.
Holmes' function in the story is to solve problems by detective work. In Doyle's stories, normally, someone visits Holmes with a mystery or a problem, and Holmes uses his expert knowledge to find a solution, as he does in the Red Headed League.