A central business district (CBD, also called a central activities district) is the commercial and often geographic heart of a city.^{[citation needed]} In the United States this part of a city is commonly referred to as "downtown" or "city center".^{[citation needed]} "City centre" is commonly used in Canada, Ireland and the United Kingdom.

The term CBD or Central Business District is the central district of a city, usually typified by a concentration of retail and office buildings.

The term city place is similar to CBD in that both serve the same purpose for the city, and both are marked by a higher-than-usual urban density as well as often having the tallest buildings in a city. City centre differs from downtown in that the latter can be geographically located anywhere in a city, while a city centre is generally located near the geographic heart of the city. London arguably has three city centres, the City of London, the medieval City of Westminster and the transformed Docklands area. Mexico City also has more than one city centre: Centro Histórico, the colonial; Paseo de la Reforma - Polanco (Mexico) the mid-late 20th century CBD, and Santa Fe, the new CBD. In Taipei, Taiwan, the area around its main railway station is regarded as the historic city centre while the Xinyi Planned Area located to the east of the said railway station is the current CBD of Taipei and not only is it considered the financial district of Taipei, but it is arguably the premier shopping area in Taipei and Taipei's most modern cosmopolitan district. Taipei 101, Taipei's tallest building and currently the world's second tallest habitable skyscraper, is located in Xinyi Planned Area.