how DOES facebook know me so well?

Sometimes Facebook will tell me that users who share my interest in THE SMITHS are also fans of MORRISSEY. Or that users (like me!) who enjoy NEW ORDER also like JOY DIVISION.

This strikes me as kind of ridiculous, because if I like New Order so much that I have included them in my fb profile, then I probably am already aware of Joy Division’s existence. But, fine.

Then today, Facebook informed me that users who like WRITING also like READING.

There is something weird going on with this algorithm.