When an author describes the ways in which two things are alike, he or she is _____ them.

When an author describes the ways in which two things are alike, the process is known as comparing. This involves identifying similarities between the two subjects being discussed. Comparing allows the author to highlight aspects such as shared characteristics, themes, or functions, thereby enhancing the reader's understanding of both items.

In contrast, contrasting focuses on the differences between two subjects rather than their similarities, which is not applicable in this scenario. Comprehending pertains to the understanding of material, but it doesn't directly relate to the act of drawing parallels. Describing generally refers to providing details about a single subject rather than making a comparison. Therefore, comparing is the most accurate term to describe the action of identifying how two things are alike.