Although our lives don't depend on whether or not we understand every nuance of grammar, clear communication can. It is fairly easy to differentiate between a noun and a verb, but knowing a preposition from a conjunction is more difficult because their purpose in a sentence is so similar.


Prepositions are words that work together with nouns and pronouns to create phrases (prepositional phrases) that show a spatial, temporal, or directional relationship between elements in a sentence. A preposition will always be accompanied by an object. Prepositions can show relationships of time, such as "Marty was talking during the movie. In this case, "during" is the preposition. Prepositions can also show spatial relationships, like in the example "Abigail is near the dessert table" or "The book is under the table." In these sentences, the words "near" and "under" serve as prepositions. Other common prepositions include of, in, on, over, toward, until and for.


Conjunctions join words, phrases or sentences. There are three main types of conjunctions: coordinating, subordinating, and correlative. Coordinating conjunctions link equal elements; these are words like "and," "but", "or," "for" and "yet." Subordinating conjunctions link independent clauses to subordinating clauses. These include words like "although," "after," "because," and "while." In the example "While I was sleeping, the children vandalized the house," the word "while" is the subordinate conjunction. The final type of conjunction is the correlative conjunction. This kind of conjunction pairs words to link elements, and includes "either/or," "neither/nor" and "not only/but also."