The application allows you to communicate with any of your contacts to see your face and show theirs (provided you have front and rear camera) and can therefore communicate by voice over the loudspeaker of the phone itself. This is like the the helmet microphone which is very useful if you are in the street.
In addition to video conferencing, which are the star of the application, we can also send instant text messages to communicate more fluently with any other user of the service (for which we will need credit, of course).
Skype works on any terminal Android 2.2 or higher. Because it needs access to the benefits of front and rear camera, you will need at least version 2.3.