A commercial district or commercial zone is any part of a city or town in which the primary land use is commercial activities (shops, offices, theaters, restaurants and so on), as opposed to a residential neighbourhood, an industrial zone, or other types of neighbourhoods. In some cities, authorities use planning or zoning laws to define the boundaries of commercial districts.

In the United Kingdom, commercial districts that are primarily for shopping are called high streets. In North America, in smaller towns and cities there is often only one main commercial district, which is located on the main street. In larger cities and towns there may be multiple commercial districts, often with more specialized functions. If a city has one large central area of offices and professional buildings, this is called the Central Business District or CBD (term used especially, but not exclusively, in Australian and New Zealand English), or downtown (North American English with the exception of Liverpool, England, who also uniquely use the term 'downtown' [1]). "CBD" and "downtown" usually refer to centrally located areas of a city and are of predominate importance within their city, which differentiates them from other commercial districts. The financial district of a city is the specific area of either a larger CBD or downtown or separate zone and would typically house a stock exchange or several bank headquarters. Likewise, city centre is sometimes used as a synonym for CBD or downtown, but often the geographical centre of a city not a commercial district. Often the centre of a city in older cities is full of historic, institutional, or cultural areas.