Preposition- a word governing, and usually preceding, a noun or pronoun and expressing a relation to another word or element in the clause, as in “the man on the platform,” “she arrived after dinner,” “what did you do it for ?
Prepositional Phrase- a modifying phrase consisting of a preposition and its object.
Infinitive- the basic form of a verb, without an inflection binding it to a particular subject or tense
