If you want to express the idea of ending-finishing-stopping something, you can use one of several specific verbs. The most basic verb is кончать/кончить.

Just like начинать/начать, this verb can be complemented by either a noun or an infinitive phrase. In either case the person finishing the process appears in the nominative. When working with nouns, the thing that ends is in the accusative case:

When using an infinitive phrase after this verb, that infinitive MUST be an imperfective infinitive:

Here is where things get odd. It turns out that in colloquial Russian кончать/кончить also means “to have an orgasm, to come.” This occasionally leads students into difficulty. Just imagine some poor American student back in the eighties studying assiduously at Moscow State University. One day he glances up and asks his teacher whether she had finished her comments by saying «Вы кончили?» She takes it the wrong way. All of the sudden her cheeks turn red, and the poor student glances at her in confusion, but then at lunch time he finds her slipping her hand into his, and they spend the rest of the summer taking furtive trips to Leningrad until her ex-boyfriend starts stalking them. Actually the ex-boyfriend turned out to be a decent guy, once I plied him with enough Georgian wine. It turns out that he really wasn't all that much into her and was just stalking her out of principle. He was happy to vanish forever once I slipped him a hundred samolians. But then Lena stopped talking to me and I started following her home and —

Um… well, you get the idea. Anything can happen when you don't know the various meanings of the words you use.

Nowadays Russians use the verb заканчивать/закончить more often than кончать/кончить. It works exactly the same way, is perfectly regular, and does not have that problematic secondary meaning. Thus all those sample sentences above can be rephrased with заканчивать/закончить without any change of meaning. The кончать/кончить versions are perfectly grammatical; it's just that the other verb is slowly supplanting it.

One thing that you CANNOT do is to use either of these verbs in the sense of “The movie ended at 5:00.” For that you must use the reflexive forms of the verb, which we will discuss tomorrow.