The initial Facebook usage was indeed driven by dating type activity – checking people out, learning more about crushes, light stalking type of activity, etc.
The larger picture here is that Facebook created a high utility online service for enabling pre-existing social behaviors within an offline community. This makes for an interesting lesson learned: it’s easier to piggyback off a pre-existing community with offline behaviors that drive online service usage.
Facebook also placed limits on the ability to search or browse users to the college that the user attends. These measures aim to make users feel that the site is exclusive and limited to members in their offline community (colleges and universities).
http://www.startup-review.com/blog/facebook-case-study-offline-behavior-drives-online-usage.php


