What is this residential college system? Can you explain the differences between each one?
As a freshman, you are randomly placed into one of the 6 residential colleges. Mathey and Rocky are somewhat similar, with older dorms, but probably the most beautiful gothic architecture on campus. Wilson is known for having the worst dorms, but the best central location on campus. Butler is also somewhat central, but has a collection of much newer, nicer dorms. Whitman is the newest college, with air-conditioned rooms, but a somewhat winding/dark layout. Forbes, often the subject of many “worth the walk?” jokes, is the farthest residential college, in the far southwest corner of campus.
Just to expand on @gumali’s comments, the residential college you end up in will give you the most immediate sense of community on campus as you adjust to college life. Freshmen and sophomores are welcome to eat in any of the residential college dining halls, but people tend to stick with their own RC’s dining facilities, where you can pop in at any point in a meal and find people that you know to sit down and chat about the day.
Also, each of the residential colleges have common space where you hang out and relax, study closer to home than walking all the way to Firestone library.
As a side note, I was a member of Wilson College and was a manager at the Butler/Wilson dining hall for all four years. Wilson is definitely awful, terrible, horrible housing, but at the end of the day, many years after graduation, it’s not that big of a deal. It’s still Princeton.