A preposition is one of the eight parts of speech. The preposition serves as a dab of glue, sticking a noun, a group of words acting as a noun, or a pronoun onto the sentence. The noun or pronoun stuck to the sentence is called the object of a preposition. Together they form a prepositional phrase.
We have three kinds of prepositions: (1) simple prepositions, (2) marginal prepositions, and (3) compound prepositions.
Simple prepositions are one-word structures; most have only one syllable, as in for, in, of, with, to, from; some have two, as in after, before, under; some have more, as in underneath, notwithstanding. We have about 70 simple prepositions in the English language.
Marginal prepositions act just like simple prepositions, but they are derived from other words, primarily verbs, as in barring, including, concerning.
Compound prepositions come in two- or three-word varieties, as in pursuant to, according to, for the purposes of, in conjunction with. Watch out. Don't use a compound preposition like with respect to when you simply mean for, with, about, or some other simple preposition. Henry Fowler, the great English grammarian, called compound prepositions “the compost of our language.”