To classify is to gather into types, kinds, or categories according to a single basis of division.Mailroom personnel, for example, might separate incoming mail into four piles: orders, bills, payments, and inquiries. Once the mail has been divided in this manner-according to which department should receive each pile-it can be efficiently delivered.

The same information can be classified in more than one way. The Census Bureau collects a variety of data about the people living in the United States. One way to classify the data is by age group-the number of people under eighteen, between eighteen and fifty-five, over fifty-five, and over seventy.

Such informationmight be useful in developing programs for college-bound youth or for the elderly. Other ways of dividing the population are by geographic location, occupation, family size, level of education, and so on.

Whether you classify rocks by their origin for a geology course or children bytheir stages of growth for a psychology course, you will be organizing large groups into smaller, more manageable units that can be explained to your reader.