По??? How many meanings does this word have?

Question

So, this word has caused many problems for me. I just can't find any good explanation of this very vague word. Some same that it means moving across the surface of an objects, others say it's like a "distributive" property preposition????? If someone could just provide a detailed explanation on this would, that would be great!

Answer 1

The preposition ПО has a few meanings, and it usually governs the Dative case:

1)     along, on: Я шёл по улице.

2)     Around, in different directions: Он бегал по комнате.

3)     On the surface: Он постучал рукой по столу.

4)     According to: По закону он должен вернуть деньги. Самолёт вылетел по расписанию.

5)     By means of communication:  Можно я позвоню вам по телефону?

6)     Related to some sphere of activity, field of knowledge: Она специалист по местному законодательству.

7)     When it is necessary to show the regular action repeated on some days or periods of time:

По четвергам они ходят в спортзал.

8)     Shows the reason, similar to the meaning of “due to, because”: Я сделал это по легкомыслию.

Answer 2

It's helpful to keep in mind that various propositinos can take more than one case, and each case produces a different meaning. Take the preposition в. When it governs the prepositional, it expresses location, but when it takes the accusative, it expresses motion.

Similary, the preposition по texpresses different meanings when it takes different cases. The most common use of this preposition is indeed to express motion on a surface, as "Он шел по улице." However, it can also have a distributive meaning, as in "Учитель роздал студентам по карандаш." "The teacher gave each of the students a pencil." In that meanng the preposition takes the accusative case.