<p>MIT2010, eventually all of this will become clearer. You'll receive mailings over the summer and into the fall that will help it make more sense. For now, how about checking out the courses offered in various departments (known as "Courses") here -- 21W and 21L can be seen there as "Writing and Humanistic Studies" and "Literature" respectively. CI-H courses are usually writing classes (see here).</p>