Shot reverse shot

Shot reverse shot is a film technique where one character is shown looking at another character (often off screen), and then the other character is shown looking back at the first character. Since the characters are shown facing each other in opposite directions, the viewer assumes that they are looking at each other. 

http://www.youtube.com/watch?v=cvof8mI6pXk&feature=related


^ A Youtube link which shows basic shot reverse shot within 'Amst 109'