The document discusses the differences between gerunds and gerund phrases. A gerund is a verb form ending in "-ing" that functions as a noun, and can take the roles of subject, direct object, subject complement, or object of a preposition. A gerund phrase consists of a gerund along with any modifiers, pronouns, or noun phrases. Examples are provided to illustrate gerunds and gerund phrases functioning as subjects, direct objects, subject complements, objects of prepositions, and appositives.