We all know that companies collect "anonymous" data about us every day. Our buying records, medical records, census data is all used to find trends, market products and plan for the future. This data is supposed to be "sanitized" by removing Personally Identifiable Information (PII).
It is now coming to our attention that what we once thought was anonymous may be easily tracked right back to us. Using far less information than you once thought. According to one paper, you can uniquely identify a person with high accuracy just by knowing their ZIP code, birthdate, and sex. This information is easily retrieved from default Facebook pages.
This is definitely something that should be taken into consideration when sharing information. It is interesting that information that appears to be benign, like birthdays and zip codes could be used to uniquely identify someone in anonymous data.
Be safe and stay aware of how your information could affect you.