What are exactly fraternities?

[vinz]

Hello,
My name is Vincent Lambert. I’m 20. I'm French. I study in Paris.
I'm currently doing some research about fraternities and sororities. But this whole system seems to be really particular to the US, so I've got some questions... Would be nice if you took a few minutes to answer.
- How exactly are fraternities organised ? Do fraternities(chapters) from different colleges have any relationship? What about the different fraternities at the same college?
- Are fratenities (and sororities) the only associations you've got ? In France we've got a great variety of associations : in fact there's almost one association for each project! But ours seem to be much less developed than yours (I mean that we can belong to many of them, because we don't have to spend a lot of time for each one). You seem to be spending all your time and energy either working or having fun within your fraternity... So my guess is that fraternities are like super-associations, which have many different activities. Is that right?
- Are there houses where all members of a fraternity meet? sleep ? have parties ?
- Are some/all/any fraternity mixed ?
- Are fraternities only for undergraduate?

And to finish with I have a question which is not particularly linked with fraternities : parties at college... Are they like movies show? I mean lots of people getting drunk (it is the case in France), even girls (not the case here), having sex in the rooms above (not so much the case here...)? Which movie would be the closest to reality according to you? Do fraternities often organise parties?

Well I guess it must look weird to ask all these questions. The thing is that we do have some images of the life on US campus, but through movies mainly... so it’s very vague and probably wrong.
I would love to have the point of view from an actual American student. It would be very helpful.
Thank you for your help.
Sincerely
Vincent Lambert