You probably know that sites like Facebook are using the information they have about you - like your age, gender and interests - to serve up ads that are most likely to appeal to you.  That's a little bit harmless and perhaps even helpful.  But how about the more subtle filtering that is going on that you may not be aware of?  Search engines are using information they have about you to show you news that these search tools think will most likely appeal to you based on your previous search activities.  The problem with that?  You might find yourself living in a bubble - sheltered from ever hearing about things that might you might now agree with, but which might also open your mind a bit and make you what your parents always wanted for you - to be "well-rounded".