This document defines and explains the use of to infinitives in English grammar. It begins by defining to infinitives as verbs preceded by "to", such as "to sing" or "to go". It then lists several verbs that must be followed by a to infinitive, such as "want", "plan", and "hope". The document outlines different patterns that to infinitives can take, including subject+verb+to infinitive. It also discusses where to infinitives can be placed and their different functions as objects, subjects, subject complements, and complements of nouns and adverbs. In closing, it invites any questions about to infinitives.