Many types of in-person or telephone contacts between police and citizens are possible:

Examples: Questions from citizens to police officers in the field, public assists such as pushing a stalled vehicle out of traffic, telephone requests for police information, reports of crime or disturbance with few details, calls by detectives to witnesses or victims, reports of missing people, calls by business people to fraud detectives to report bad checks, simple traffic stops and reports of found property are a few examples of what would be considered a contact.

Some contacts with the public fit the following definition and are termed incidents or calls for service: an event occurring in or near the City of Tucson to which one or more Tucson Police employees must respond to evaluate or take action, or an event that comes to the attention of police or is initiated by police that requires formal documentation (e.g., case report, supplemental report or accident report).

Examples: Citizens reporting a shooting, citizens reporting a traffic accident with injuries, citizens reporting a burglary, citizens reporting a ringing alarm bell, officers finding a stolen vehicle, detectives making an arrest, officers searching out and arresting a fugitive, citizens reporting a neighbor problem or suspicious activity.

All calls for service receive a unique case number which serves as the incident identifier for police reference. Upon investigation, some calls for service are called crimes.

Not all police contacts with the public are calls for service, and not all calls for service are crimes.