Shot size is how far the camera is from the subject. Far away, you see the person's relationship to their surroundings; up close, you see the emotion on their face. Change the distance and you change what the audience feels.

From far to near, there are five common sizes: wide shot (the person is tiny, the focus is the environment), full shot (the whole body is in frame), medium shot (waist up, most like everyday conversation), close-up (chest up, you can read the expression), and extreme close-up (a face or a single detail — the strongest emotion).