Skype is available on phones, tablets, PCs and Macs. It is the most popular and considered by professionals to be one of the best instant messengers. It allows you to make free voice calls and observe the caller through a webcam. Additionally, you can send text messages and redirect calls to your mobile phone via Skype. From the application level, the user can search for friends, browse their profiles and edit data. Skype allows you to synchronize contacts with your phone, i.e. add Skype friends to your address book and manage notifications.