Scotland Yard is the headquarters of the Metropolitan Police, the territorial police force responsible for policing Greater London's 32 boroughs. Its name derives from the location of the original Metropolitan Police headquarters at 4 Whitehall Place, which had its main public entrance on the Westminster street called Great Scotland Yard. The Scotland Yard entrance became the public entrance, and over time "Scotland Yard" came to be used not only as the common name of the headquarters building, but also as a metonym for the Metropolitan Police Service (MPS) itself and police officers, especially detectives, who serve in it. The New York Times wrote in 1964 that, just as Wall Street gave its name to New York's financial district, Scotland Yard became the name for police activity in London.

The Metropolitan Police Service (MPS), also officially known as the Metropolitan Police, which is still its common name, serves as the territorial police force responsible for law enforcement and crime prevention within the ceremonial county of Greater London. In addition, it is responsible for specialised tasks throughout the United Kingdom, such as UK counter-terrorism measures, and the protection of certain individuals, including the monarch, royal family, governmental officials, and other designated figures. Commonly referred to as the Met, it is also referred to as Scotland Yard or the Yard, after the location of its original headquarters in Great Scotland Yard, Whitehall in the 19th century. Its present headquarters are near there at New Scotland Yard on the Victoria Embankment.