Just how much of your information is now open for public consumption by default? You would be surprised. Before we go any further, head to Facebook and check you privacy settings; you can never be too careful.
Facebook started as a somewhat locked down website, something that the company has been running from ever since, changing its privacy structure with every major release. The more data that is private on the website, the worse the ads that Facebook can sell. More data leads to better targeting, and therefore more money for the company. Privacy is bad for business.
IBM employee and apparent infographic creator extraordinare Matt McKeon has put together a wonderful progression of the “normal” Facebook privacy settings through time. Of course, you can adapt your own settings, these are just the default privacy levels at different points in Facebook history. Take a look: