According to the text, Sunnah is classified by the way it reaches us into:
«المتواتر والمشهور وخبر الواحد»
Mass-transmitted, well-known, and solitary/non-widely transmitted reports.
This is not simply a count of narrators. Each category concerns the strength of transmission, the type of knowledge it yields, and the degree of obligation to act.
Mutawatir involves transmission by independent numerous groups; mashhur is initially limited then becomes widely accepted; khabar al-wahid does not reach the prescribed level of fame.