Identifying a 'magic moment'—a specific user behavior that predicts long-term retention—is key. For example, Facebook found that adding seven friends in the first ten days significantly increased user retention.

For social media platforms, connecting users with their friends quickly is essential; without this connection, users are unlikely to return due to an empty newsfeed.

Facebook's success was due to secure connections and ensuring that new users had at least 20 friends on the platform, which made it more engaging.

The growth and user engagement on Facebook excited me, even though I wasn't a big user myself; the metrics showed it was gaining traction quickly.

Facebook understood that the most important feature of a social network is having your friends there, which creates a tension between individual and network needs.

Facebook's success stemmed from its emphasis on real identity and the ability for users to share their content, which was missing from other platforms at the time.

The call to action should be closely aligned with the 'magic moment'—the point when users realize the value of your product and feel excited to use it.

Facebook's growth was initially slow, taking a year to reach a million users, but this time allowed us to refine the product and ensure it met user needs effectively.

Facebook's success was partly due to its high trust and real identity, which was established by starting in colleges where users felt safe sharing personal information.