It's probably a good idea to explain your college application what your extracurriculars are. Students should not assume that the admissions officer is familiar with a certain activity. While it's true that certain colleges are very familiar with a given high school, it may not be the case with other admission officers. Therefore, to be on the safe side, it is better to explain the activity in the application. This also allows a student to let the admissions officer know just how involved he or she was with a specific activity and explain it's significance. Another benefit, is that this forces students to discern which activities or clubs to list in the application. College admission officers are on the look out for serial clubbers. These students join a bunch of clubs but don't actually do anything in the club.