This document discusses clauses of purpose that begin with "to", "in order to", and "so that". It explains that purpose clauses are used to explain the reason for an action and that the most common is a "to-infinitive" clause where the subject is the same in both clauses. More formal writing may use "in order to" or "so as to". The conjunctions "so", "so that", and "in order that" are followed by a subordinate clause where the subjects can differ and are usually followed by a modal verb. Examples are provided to illustrate the different types of purpose clauses.