Facebook is about sharing memories, and "static" content. One can use Facebook to read the same "group" that has been around forever, or to looks at memories fr

Facebook is about sharing memories, and "static" content. One can use Facebook to read the same "group" that has been around forever, or to looks at memories from the day/week/month/year. As a result, it's a good fit for people who are only occasionally online. Everybody else wants to live share what's happening right now. Whatsapp is great for this, as it allows instant group chats with ephemeral ad-hoc groups. Instagram is great to share what just happened, without a UI polluted with older and unrelated content.