Illinois is in the Midwestern United States and is the 6th most populated state and the 25th largest in land area. The name derives from the Miami-Illinois verb meaning "he speaks the regular way," which was then modified by the French. Illinois borders Indiana to the east, Lake Michigan to the northeast, also sharing a water boundary with Michigan, Kentucky and the Ohio River to the south, Missouri, Iowa, the Mississippi River and Missouri River to the west, and Wisconsin to the north. Chicago is the largest city in the state, and the third most populated city in the country. Other large cities include Aurora, a Chicago satellite city, Rockford, Joliet, Naperville, Peoria, Elgin, Belleville, Champaign, and Waukegan. Springfield is the state capital and is the sixth most populated city in the state.

Illinois has 73 state parks, 12 state recreation areas, six state forests, four state memorials, two state nature preserves, four state natural areas, 26 state wildlife areas, two state wildlife management areas, two state wildlife refuges, one national forest, three national historic sites and five national wildlife refuges. Most notable are Argyle Lake State Park, Chain O'Lakes State Park, the 2,800-acre park which features seven lakes and borders three natural lakes, Moraine Hills State Park, Siloam Springs State Park, Mackinaw River State Fish and Wildlife Area, Dixon Springs State Park, Cedar Lake Park, Cache River State Natural Area and Volo Bog Natural Area, Illinois Beach State Park, and Illinois Caverns State Natural Area. There are a number of registered historic sites throughout the state, including many in the state capital of Springfield, centered around Abraham Lincoln, who lived there and started his career as a politician. Chicago has a great many attraction;, most notable and famous are Millennium Park, the Art Institute of Chicago, the Field Museum, with 300,000 square feet of biological and anthropological collections, the Museum of Contemporary Art, Museum of Science and Industry, Adler Planetarium, Shedd Aquarium, and Navy Pier.

Illinois' major agricultural products include corn, soybeans, hogs, cattle, dairy products, and wheat. Most years, Illinois is the first or second state for production of soybeans. Illinois is the second highest producer of corn in the U.S. and the third highest producer of ethanol, processed from corn. The state is the leader in food manufacturing and meat processing, and Chicago remains a large producer of these. Illinois is also a large producer of wine, with many vineyards and wineries in the southern part of the state, as well as peach and apple orchards. Illinois is a leader in manufacturing, ranked as the fourth most productive manufacturing state in the U.S. The northeastern part of the state has the majority of the manufacturers, with 18,900 manufacturing plants in Cook County. The leading manufacturing industries are chemical, machinery and food manufacturing, fabricated metal products, transportation equipment, plastics and rubber products, and computer and electronic products. Financial trading, higher education, law, logistics, medicine, publishing, tourism, and energy production and distribution also contribute greatly to the economy of the state. There are more than 15 public colleges and universities, including branches, in Illinois, as well as nearly 100 private colleges, universities and for-profit institutions, and more than 50 community colleges. Most notable are Chicago State University, Illinois State University, Northeastern Illinois University, Northern Illinois University, Southern Illinois University, University of Illinois, Western Illinois University, University of Chicago, Loyola University and Northwestern University.