This page lets you search for the most popular courses at the University of Maryland — College Park. You can search for an entire department (e.g. "MATH" for all math courses), the most popular xxx-level courses (e.g. "PHYS4" for all 400-level physics courses), or for a course with a certain number across all departments (e.g. "101" for all courses with the number 101 in them).
You can click on any course in the chart to go to its page, which includes professor reviews and grade distributions.
Course popularity is determined by the number of students who have received a grade for each course.
Data is not guaranteed to be correct. The source of the grade data can be found here.