Shot-reverse Shot

Shot-reverse shots are typically used in a conversation between two characters within a film, it is shorts edited together to alternate between the characters whenever that person is speaking. It takes us back and forth with close-up shots and it shows them talking to each other. They are usually shown facing opposite directions so that the audience can conclude that they are looking at each other (even without actually seeing them looking at each other).

Here we see a perfect example, talking to himself in the mirror, although it never actually shows it, we can easily deduce that they are looking at each other