The document discusses infinitives and infinitive phrases. It defines an infinitive as a verbal with the form "to" plus the base verb form. An infinitive phrase includes an infinitive plus modifiers and complements. The document provides examples of infinitives and infinitive phrases functioning as adjectives, nouns, and adverbs. It analyzes sentences containing infinitives and infinitive phrases and their roles. In closing, it reminds the reader of the key points about infinitives and infinitive phrases.