a group comprised of males who need to find security in a group identity/subculture.

A sort of club for bored college students for the most part. You live in a house with other members of your fraternity and go to their parties which consist of underage drinking and other rebellious behavior. Pretty much anyone can join these. There are a few which are more specialized/focused on special interest however. You usually need a certain GPA, college major, religious/political belief, etc, to even be considered for these, and these are the ones that make the connections and produce very powerful people. Some of these fraternities are often associated with conspiracy theories due to their secrecy and character of their members.

A sorry excuse for on-campus participation in clubs and a form of 'purchasing' friends or as they are known amonst themselves...'brothers', for life; in which their frats always has to revolve 2-3 greek letters, revolve around a 5 party school weekday with different types such as a 'kickback' or a 'hoe-down'...with non-stop spirits all night

The fraternity is a dying breed. With notherners thinking that hair gel, popped collars, and abercrombie is cool, it is obvious why many people look down on fraternities. Southerners, however, are doing their best to keep the tradition alive. "You don't like us because you are not a part of us, and you are not a part of us because we don't like you."
take a look at www.fratty.net

A group of fucking douchebags that think they are better than anyone that is not a part of their fraternity and are the kings of hazing kids to death and treat girls like shit because they have absolutely no respect for humankind. Boys have to pay to go to their parties or they even get told to fuck off by the cool ass frat brothers, girls get in for free. They changed for the worst, they potentially were good people in high school.

douchebags befriending douchebags with the intent of engaging in acts of douchebaggery together

A group of male college students who claim to uphold the ideals of Ancient Greece in their daily lives. Oftentimes, they actually do just this, and their members are much more cultured, kind, and devoted than the general public. However, there are some severely fucktarded ones that cater to the stereotype of groups of boorish womanizing idiots walking around calling everyone who isn't in a fraternity a GDI. There are some notable differences between these two types of fraternities:

1. Everyone joining a fraternity gets hazed. However, the second type usually subjects recruits to perverted and disturbing methods, and usually treats them like throwaway peons instead of potential brothers.

2. Members of the first type generally care about getting good grades. Members of the second are too busy thinking about how awesome they are for having so many friends.

3. Members of the first type care about appearing to be productive members of society. Others are in it to bang dumb sorostitiutes and get drunk/high, and care nothing about "Greek ideals"

4. Members of the first type are likable. Members of the second type aren't, and should be cornered and beaten when none of their friends are around to flaunt how worthless they really are.