As an international student, I am excited to see such a good transportation system in Chicago. The Chicago Transit Authority (CTA) comes under the Regional Transport Authority (RTA), which is the second largest metropolitan transport service in the United States after New York. It connects almost forty suburbs and the city of Chicago. It has almost 2,000 buses which get connected to 3,000 km (or just under 2,000 miles) of the city's roadways. The world's busiest airport is the O'Hare International airport. To reach the airport from downtown, the CTA Blue Line provides a rapid transit which is approximately 40 minutes from the Loop.
To move around the Chicago downtown area, there are so many public systems available such as Divvy, CTA Bus, CTA Train (the elevated train or simply the "L"), Pace Bus, or the Metra. One can go around the downtown at any time they choose. One doesn't need to take a car or any other transport. They can use the public transport anytime they need.
If you like to go cycling, Chicago has separate lanes for cyclists to move around the city. Chicago has a connected network of 290 miles of bike lanes. The main observation from my point of view is that people should not get into accidents going in the public or private roadway. As I mentioned before, Divvy is the shared bike system one can use.
Also, individual owned bicycles are permitted on CTA buses, so people don't need to worry about carrying the bicycles in the car or any other vehicles. For example, if you are from the middle of the downtown area, and you want to drive your bicycles to the Lakefront shore, you can take the CTA buses and reach the Lakefront trail and have an amazing ride along Lake Michigan.
The rail system provides a wonderful experience, it gets connected to almost every place in the downtown. Most times, trains will come every ten minutes, so you do not need to worry about waiting overly long.
As an international student, you will be offered to avail the Ventra card which gets activated once your semesters starts. You can use the card multiple times throughout the semester. It ends after your semester end date. Most of the students take the Ventra card which is $155 throughout the semester, which allows easy travel around Chicago.