Recs.
Updated
Skype is a VoIP and IM client. The service allows users to communicate with peers by voice using a microphone, video by using a webcam, and instant messaging over the Internet. Phone calls may be placed to recipients on the traditional telephone networks.
SpecsUpdate
Pros
Pro Screen sharing
You can show your whole desktop, a select part of the screen or a specific window over Skype.
Pro File sharing
Skype allows you to send any files (MP3s, images, text, etc.) by simply dragging and dropping then in the chat window making it simple to share things with colleagues.
Cons
Con Subpar video quality with more than 5 users
Skype has significant problems with multiple users and video quality. Skype recommends that a max of 5 users group chat as video quality is severely affected. Even webcams tested with other chat services showed lower quality when used with Skype.
Con Requires both ends to be online (if neither end is using a cloud-enabled device)
Messages are sent and received only when both ends are online, if neither end is using a cloud-enabled device. In this case, if you are online 9-17 and your recipient is online 18-3, messages will never be delivered.