How many instant messengers are installed on your phone? One, two, five? If we assume that each social network has its own built -in messenger, then you can add them. And this whole team of applications send us notifications daily. Dozens of notifications of new messages. Let's see how Slack stands out among such services. Why not "another messenger" Take, for example, Telegram. Exclusively as an example. But you can easily take the WhatsApp or Viber sample.