As a student I can use to receive online classes from someone far away or talk with a far away fellow student, or even with one who is at home.
Skype allows you to start a video chat or only a written chat or even a mixture of both. You can also share documents through it, or only speak and not use video or viceversa.
The requirements are a good grafics card and a decent CPU to manage the video processing. Of course a good internet connection is also primordial to have fluent communication.