The document summarizes the uses of the infinitive "to" form and the "-ing" form in English grammar. 1) The infinitive "to" is used to express purpose or intent after certain verbs, adjectives, nouns, and pronouns. 2) The "-ing" form is used as a noun or gerund after certain verbs to express preferences, and after prepositions and verbs like "spend" and "see". 3) Both forms are used in different constructions like "too/enough to", "be the first to", and "spend time doing" something.