Paragraph development by classification helps us sort out information about a subject into logically related categories according to some specifically shared quality. Through classification, the most prominent aspects of a subject come more sharply into focus and the dominant ideas become easier for readers to understand.
Sample:

      The term "post-secondary education" takes on a complex meaning in the United States. Our concern here is with institutions of higher education — those organizations whose major functions are to educate and to award degrees. There are five categories of institutions of higher education: Doctoral-level institutions include the large research universities and other universities with strong Ph.D. programs; Comprehensive institutions offer several programs but (usually) no degree higher than a master's; General baccalaureate (颁发本科学士文凭的) institutions are mostly small colleges whose liberal arts program dominates the curriculum; Specialized institutions consist of theological seminaries, medical schools, business colleges, and other institutions which specialize in a single field of study; Two-year institutions, whose historic term is "Junior College," are now mainly associated with those 2-year community colleges founded during the last generation.
      The total number of U.S. institutions of higher education is, at last count, 3 280. This figure represents only accredited institutions — that is, those recognized by agencies which set standards for university study.