This document defines a gerund as a noun formed from a verb by adding "ing" and provides examples of how gerunds can function as the subject of a verb, direct object of a verb, complement of a verb, and object of a preposition. Specifically, it notes that a gerund is a noun made from a verb with "ing" and uses the gerund "reading" from the verb "to read" as an example. It then lists the four functions of gerunds with short descriptions and provides examples for each function.