Boost the users ego. Facebook does this well and I have a sneaking suspicion it was never intentional. The whole impetus to create it was born out of human natu

Boost the users ego. Facebook does this well and I have a sneaking suspicion it was never intentional. The whole impetus to create it was born out of human nature and the user engagement just flowed from there. At this point people post to Facebook to show off how cool and interesting their lives are. Facebook gets this right in so many ways. It's fast, easy, and you get lots of reinforcement in the form of likes. The fact that the whole thing just naturally came together is what really made it. Unfortunately not every web app can make it flow like them. The more thought you have to put into how you'll evoke these emotions you have to put in, the more evidence there probably is to suggest your app just doesn't lend itself well to it. That said, not all apps need to evoke emotions to be successful. Serving a basic utilitarian purpose and doing it well is often enough. Google Drive comes to mind.