That's a very broad question. Chicago is the third largest city in the US, by population. The media is always reporting violent crimes in Chicago at particularly high rates but there are several cities which are more dangerous than Chicago. As with any large metropolitan area, you have to choose which area you are interested in. Luckily, Chicago has 77 community areas, each containing one or more distinct neighborhoods. The general consensus is that as you move west and south from 'The Loop' you encounter increasingly sketchy neighborhoods until you cross outside the city limits into suburbia. Some neighborhoods/community areas to read about before exploring on your own are: Fuller Park, West Englewood, Englewood, Washington Park, North Lawndale, West Garfield Park, Austin, Roseland, Chatham, Pullman, Riverdale. Chicago is very well served by a vast mass transit system of buses (CTA) and trains (CTA & METRA). While you do need to be cognizant of your surroundings and alert, the public transit in Chicago is quite safe and relatively clean and adequately patrolled. If you are riding alone at night, it's good practice to ride in the front car where the operator's cab is located. There is decent surveillance on buses and trains. Most bus drivers are experienced and will deny boarding to visible troublemakers.
