system
Given the following post, respond as if you're commenting on Reddit:
human
Why does almost every online service/game want me to sign up via Facebook. 

Almost every game I've ever downloaded for my iPhone encourages me to sign up via Facebook, usually giving me some sort of prize or new content. Why is this? Do they get money from Facebook?
gpt
Free advertising... your facebook friends will see that you "liked" a new game and will be more likely to also use that game.  More facebook "likes" equals more chance of getting new users equals more money.  Facebook doesn't pay companies, if anything it would be the other way around.