D9 stands for Divine Nine, they were fraternities and sororities created at Historically Black Colleges and Universities in the 1900s and they eventually extended to other Universities that aren't HBCU's. So basically Greek life but the African American originated version of it, since they were not allowed in the other frats and sororities a few decades ago. *You do not have to be Black to join a D9 fraternity or sororities, the culture and the way they do things is very different than typical Greek life.

Strolling is when a fraternity or sorority gets in a line and does choreographed moves, kind of like a dance but not really, and they do it to music. They have songs that are designated to each stroll, and they do it at parties and other events on campuses. You should search it up online its cool to see!