Chicago is the most populous city in the U.S. state of Illinois and the third most populous city in the United States. It's situated in the northeastern part of Illinois. Chicago is among the oldest of the world's great cities and one of the most cosmopolitan. It is the state's economic, transportation, and cultural centre. Since the 19th century, Chicago is renowned for influencing other cities around the world. It is famous for its astounding architecture and modern structures that stand side by side to complement each other. Some of the places that make it famous include the amazing buildings, Willis Tower, Millennium Park, Art Galleries, Navy Pier, and The Art Institute of Chicago.

According to the United States Census Bureau, as of 2019, Chicago had a population of 2,693,976. Compared to other cities in the United States, Chicago is considered to be diverse. The ethnic composition of the population is 50.1% White (including White Hispanic), 30.1% Black or African American, 6.3% Asian, 0.5% American Indian, 3.2% from other races, and 2.7% from two or more races. When it comes to religious beliefs, Chicago is known to be diverse as most people identify themselves as Christian, Jewish, Muslim, Hindu, and Buddhist. According to data, 71% people in Chicago identified themselves as Christian, 7% as Jewish, 2% as Muslim, 1% Hindu, 0.5% Buddhist and 18% as non-religious. As one of the most diverse cities in the United States, Chicago houses over 2.7 million residents, who collectively speak several languages, including Spanish, Polish, Arabic, Italian, German and of course English.

There is a Mayor-Council system in Chicago. The Mayor of Chicago, who is elected every four years, holds executive powers. The Chicago City Council is the legislative branch of the government of the City of Chicago and consists of 50 aldermen, one elected from each ward in the city. The Mayor and the City Council, being the city's chief executive officer and legislative body respectively, meet in the Council Chambers on the second floor of City Hall. The council takes official action through the passage of ordinances and resolutions.

Chicago has always been a commercial city and today enjoys the status of having one of the largest city economies in the United States. The city thrives in trade and commerce and has a vibrant culture steeped in commerce. It has a GDP of over $689 billion, which is about 4% of the United States' total GDP. The size of its economy is larger than that of several countries. The Port of Chicago handles over 19 million tons of cargo every year.

The city of Chicago has consistently taken positive steps towards infrastructure development. The Mayor of Chicago has been proactive in planning for growth with the publication of the city's Infrastructure Plan. It identifies a range of infrastructure priorities for Chicago, from new energy, water and sewerage infrastructure, to enhanced digital connectivity and new rail and road schemes. Some of the investment is provided by the private sector, through the privatized utilities. This has generally worked well in Chicago, although the business is particularly concerned at the lack of capacity in digital infrastructure. The take-up of high-speed broadband by business is comparatively low; and just over 5% of premises cannot access superfast broadband in the first place, with these not spots particularly prevalent in the Downtown Chicago.