A police service (or force), is a body of government sanctioned and empowered by the State to enforce the law, limit civil disorder, protect property, individuals and ensure order within the society. Unlike the military, the police is limited to keeping the order inside the country and in some cases, such as Ireland or United Kingdom, police do not carry fire arms and are not authorised to use them. In the case where the firearms are needed in the United Kingdom and Ireland, the Authorised Firearms Officers are called to assist. Some of the lesser known police roles include nurse, press officer, helicopter pilot, crime scene manager and horse trainer.

The two countries with the highest number of police officers are People's Republic of China and India, due to their large populations.

The police officers have a range of duties that encompass keeping the civil order, such as traffic control, crowd control, investigations, and protection of civilians as well as property, among others.

Although police is an integral part of a well governed society, the incidents of police brutality have dominated the headlines recently, especially in the United States. The United States police are authorised to use the deadly force, which can toe the line between the necessary and excessive use of force.

Some argue that the official way the police are referred to, might be a clear indicator of how the police operates. For example, the police across United States is generally referred to as the Police Force, while the police in the United Kingdom is referred to as either Police Service or just Police. This is an important indicator of the way police is looked upon in these places, as either a public service or a force, which can be argued, influences the way police behaves.

Since the population relies on police officers for protection and help, the friction between the communities and the police are especially dangerous, as it can lead to bigger public unrest, as recently demonstrated in the Ferguson protests.

Although the police has been installed to 'serve and protect', there are still many areas where serving and protecting still has a long way to go.