Historically you needed to be an on campus student to join a sorority. These groups consisted of young women who lived in a single residence and participated in various activities, generally around a specific, sorority related theme.
There are social sororities that focus on social events and gatherings. There are also academic sororities where grades are important and a minimum grade point average must be kept.
Sororities function as families. The members are encouraged to care for and encourage one another.
The benefits of having a group of like-minded individuals can be both distracting as well as affirming. The members can all help one another attain goals that might be difficult to accomplish alone. It is also a way to forge business connections for life after graduation.
Many sororities have joined the computer age in that they allow distance education students to join. Generally, those students would attend gatherings of a local chapter of their sorority even if it was at a different college.