Prepositional case. The prepositions в, на, о, об

1. Russian uses three prepositions with the prepositional case:
   в, во - in, at
   на - on, at
   о, об - about
2. We use the preposition в primarily to indicate a location that is generally an enclosed place, or a palce that has some kind of a border:
   дом, квартира, Америка.
3. We use the preposition на to indicate location that is usually some kind of a surface or an activity that one can attend:
   площадь (square), улица (street), лекция (lecture), концерт (concert), урок (lesson).
4. We also use the preposition на with the directions of the compass:
   север (north), запад (west), восток (east), юг (south).
5. Another use of the preposition на is to indicate playng of an instrument:
   Она играет на гитаре. She plays the guitar.
6. There are always exceptions to the rule regarding the use of the prepositions в and на. These nouns will take the preposition на, although they designate enclose places:
   фабрика (factory), почта (post office), станция (station), вокзал (train station).
7. We use the preposition o with nouns that begin with a consonant, and об with nouns that begin with a vowel:
   о газете, о Москве, but об институте, об Америке.