<p>There are different types of fraternities and sororities. The oldest fraternity, Phi Beta Kappa, was started in 1776 as an academic society for young men at the College of William & Mary to come together and engage in debate and oratory (public speaking), as well as possibly to discuss Revolutionary politics. There are a lot of academic fraternities and then there are some fraternities and sororities that blend academic/professional interests and social ones. Two examples are Sigma Alpha Iota and Phi Mu Alpha Sinfonia, a sorority and fraternity respectively that were founded for serious music students to fellowship together.</p>
<p>The ones you are probably thinking of are primarily social fraternities/sororities. From the mid 19th to the early 20th century, a spate of Greek-lettered organizations were begun in the style of Phi Beta Kappa. Young men (and later, young women) would get together for various reasons. Many of them originally began to bring together serious young scholars at colleges and universities so that they could read and discuss literature together and engage in debate, like PBK, but eventually moved to more social and sometimes political issues. Sororities were often begun because young women were at co-ed universities and needed to band together for support. The Greek letters are usually the first letter of each major word in a motto that is kept secret, known only to members).</p>
<p>Today, the members may have something in particular in common or nothing at all, other than that they are members of the same group. For example, Alpha Epsilon Pi was originally founded by Jewish men on Jewish principles, but these days anyone can join. Alpha Chi Omega was originally started for students with connections to the music school, but later expanded to include any woman. Today, the way that the groups do intake (especially the NPC sororities) ensures that most of the groups don’t require any kind of thing in common ahead of time. Basically, it’s just college students who want to develop bonds of brother or sisterhood, engage in the deep and storied traditions a lot of these groups have, and establish some kind of network that often extends past college. Some join because it’s a family tradition (George W. Bush joined Delta Kappa Epsilon like his father, George H.W. Bush; Laura Bush was a member of Kappa Alpha Theta, and her daughter Jenna subsequently joined as well).</p>
<p>Many times fraternities and sororities have houses on or near campus, where some of the members live together. But many fraternities don’t have chapter houses. Sometimes they live together in suites in residential housing, and sometimes they don’t live together at all.</p>