Have you ever been frustrated at the lack of choice that you have in choosing your classes. My high school course selection followed premeditated tracks that had courses spelled out for 4 years, with room for an elective here and there. And if a class wasn't going to well or didn't turn out to be what you thought it would be, you were out of luck and had to tough it out for an entire school year.
Enter the Add/Drop period. College course selection already has exponentially more choices than any high school course selection could, and within a certain period of time, you can add and drop classes as you please. Let's say you thought you were destined to become the next great economist, but with time commitments from extracurricular, work from other classes, and the difficulty of the class you find yourself struggling to stay afloat. You can simply drop the class, and then re-enroll in it next semester when your schedule works out better. Or if you heard from your roommate that there's a really cool class in the sociology department that's right up your alley but you hadn't registered for it, you can always add it to your course load.
One of the best things about College is the flexibility and freedom you have to choose a course of study that fits to your interests, and not having to be stuck to what courses you initially signed up for at the beginning of a semester only adds to the individual educational experience. Whether you need to lighten a workload, develop a new interest, or just want to try something new, the Add/Period is just the thing for you.