Discovery is crucial.<p>A social network can be thought of as a kind of search engine: you&#x27;re trying to find people, posts and resources that are relevant to your interests.<p>On the other hand, a social communication app works by allowing you to connect to your existing friends. So for example, with an app like Peach, finding new people or searching for posts matters less.<p>The really hard question for the first case is: how do you combine searchability with end-to-end encryption?