It's equivalent to email, but more convenient if you only know the people through facebook. E.g. I admin a facebook group, so admins have a chat to discuss grou

It's equivalent to email, but more convenient if you only know the people through facebook. E.g. I admin a facebook group, so admins have a chat to discuss group-related things. If I don't have notifications enabled it's because I don't want to be distracted. I check my phone often enough, I don't need to immediately stop what I'm doing to read a message. Equally. When I send a message to someone, I don't want to distract them either. Of course there's no sophistication (e.g. busy mode, notify for messages flagged urgent only) because facebook wants people to drop whatever they're doing and use facebook instead.