A central business district (CBD) is the commercial and business center of a city. It contains commercial space and offices, and in larger cities will often be described as a financial district. Geographically, it often coincides with the "city centre" or "downtown". However, these concepts are not necessarily synonymous: many cities have a central business district located away from its traditional city center, and there may be multiple CBDs within a single urban area. The CBD will often be highly accessible and have a large variety and concentration of specialised goods and services compared to other parts of the city.
In Chicago, the Chicago Loop is the second-largest central business district in the United States. It is also referred to as the core of the city's downtown.