This is a key step in writing a classification essay. To classify, or sort, things in a logical way, find the categories to put them into. For example, say you need to sort the stack of papers on your desk. Before you would put them in random piles, you would decide what useful categories might be: papers that can be thrown away; papers that need immediate action; papers to read; papers to pass on to other coworkers; or papers to file.
Remember: In a classification essay, the writer organizes, or sorts, things into categories. There are three steps to remember when writing an effective classification essay: organize things into useful categories, use a single organizing principle, and give examples of things that fit into each category.