The Loop, one of Chicago's 77 designated community areas, is the central business district of the city and is the main section of Downtown Chicago. Home to Chicago's commercial core, it is the second largest commercial business district in North America after Midtown Manhattan in New York City, and contains the headquarters and regional offices of several global and national businesses, retail establishments, restaurants, hotels, and theaters, as well as many of Chicago's most famous attractions. It is home to Chicago's City Hall, the seat of Cook County, and numerous offices of other levels of government and consulates of foreign nations. The intersection of State Street and Madison Street is the origin point for the address system on Chicago's street grid. Most of Grant Park's 319 acres are in the eastern section of the community area. The Loop community area is bounded on the north and west by the Chicago River, on the east by Lake Michigan, and on the south by Roosevelt Road.

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 center" or "downtown". However, these concepts are not necessarily synonymous: many cities have a central business district located away from its commercial and/or cultural center and/or downtown/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 specialized goods and services compared to other parts of the city.