What is Sherlock Holmes's profession in Arthur Conan Doyle's stories?

Sherlock Holmes's profession in Arthur Conan Doyle's stories is consulting detective.

Holmes explains that he is the world's only consulting detective: when official investigators or private clients face a difficult case, they seek his advice. He studies clues, reconstructs events, and applies observation and deductive reasoning rather than serving as a regular police officer.

The profession places Holmes between the public and the police. Scotland Yard detectives, especially Inspector Lestrade and Inspector Gregson, sometimes bring him problems they cannot solve. Holmes may criticize their methods, but he also works with them and occasionally helps secure convictions.

Readers sometimes call Holmes a private detective, which is broadly understandable but less precise than Doyle's wording. Holmes does accept private commissions, yet “consulting detective” is his distinctive professional title. Dr. John Watson records the cases and supplies much of the narrative voice, while Holmes supplies the investigative expertise.