An order of importance paragraph is one in which the writer lists his supporting details in ascending or descending order of importance. In other words, the writer lists the details from least to most important or from most to least important.
The topic sentence and the conclusion are not part of the ordering. Ascending order of importance is most effective when the writer wants to make the strongest point toward the end of the paragraph for emphasis. This method employs a building effect in which points get stronger. Descending order is most effective when the writer wants to give the best detail first to capture the reader's attention.