A Police bicycle is a land vehicle used by police departments, most commonly in the form of a mountain bicycle. They are designed to meet the requirements unique to each department.

The maneuverability of these vehicles on crowded sidewalks and their ability to navigate narrow, crowded driveways offer advantages over cars, although a bicycle's top speed is lower.

Bicycle patrols are more common in temperate urban areas where limited coverage areas are available. The use of bicycles instead of cars can make police officers more easily approachable, especially in low-crime areas. Bicycles can also be issued to police officers to enhance the mobility and range of foot patrols. Bicycles are also effective crime-fighting tools when used in densely populated urban areas. The bikes are nearly silent in operation and many criminals do not realize that an approaching person on a bike is actually a police officer. Furthermore, if the criminal attempts to flee on foot, the riding police officer has a speed advantage while able to quickly dismount if necessary.

A police officer (also known as a policeman or policewoman, and constable in some forces, particularly in the United Kingdom and other Commonwealth nations) is a warranted employee of a police force. In the United States, "officer" is the formal name of the lowest police rank; in many other countries "officer" is a generic term not specifying a particular rank, and the lowest rank is often "constable". Police officers are generally charged with the apprehension of criminals and the prevention and detection of crime, and the maintenance of public order. Police officers may be sworn to an oath, and have the power to arrest people and detain them for a limited time, along with other duties and powers.

Some police officers may also be trained in special duties, such as counter-terrorism, surveillance, child protection, VIP protection, and investigation techniques into major crime, including fraud, rape, murder and drug trafficking.

Responsibilities of a police officer are varied, and may differ greatly from within one political context to another. Typical duties relate to keeping the peace, law enforcement, protection of people and property, and the investigation of crimes. Officers are expected to respond to a variety of situations that may arise while they are on duty. Rules and guidelines dictate how an officer should behave within the community, and in many contexts restrictions are placed on what the uniformed officer wears. In some countries, rules and procedures dictate that a police officer is obliged to intervene in a criminal incident, even if they are off-duty. Police officers in nearly all countries retain their lawful powers, while off duty.