Today, when and a day does not pass without communication in the internet, it is very important to know that safety here mre than anything. In fact not simply separate phrases can become well-known to the extraneous people, and even numbers of cards of bank, passwords, personal data. I prefer Viber, for example. Everything can be deleted, at what both for itself and for a man with that correspondence. Especially as a few years ago, they entered an encipherement in dialogues. It promoted safety far.