A framework for understanding the benefits and limitations of different digital identity models. The one question Elon Musk wanted answered before acquiring Twitter was: How many Twitter users are bots? While it proved to be a particularly difficult question to answer with precision, the broad response was "too many". But why are there more bots on Twitter than on Linkedin or Facebook? Partly because Twitter doesn't expect users to use their real identities. Why is that the case? And conversely, why should we need to use them on Facebook or Linkedin?