Field operations have two primary functions: patrol and investigation. Patrol aims to prevent and deter crime through community policing strategies like random patrols and computerized crime mapping. Investigation focuses on apprehending offenders and solving community problems related to crime and disorder. Key developments that professionalized patrol include increased use of patrol cars in the 1930s and crime reporting standards. Research on patrol methods found that random patrols had little impact on crime rates and citizens felt equally secure regardless of patrol levels. Differential response programs classify emergency calls by priority to ensure efficient response.