Who can see your Facebook content, if you keep to the default privacy settings? In 2010, visualization expert Matt McKeon tried to display this, showing how the privacy settings had loosened over time, and exposed your life to ever-wider groups of people.
He plotted groups of people as concentric circles, from the most intimate (you) in the centre, out to the whole world at the end. Spokes represented types of content (name, photos…), and a segment was colored blue when a group of people could see that content by default.
Thus as Facebook loosens its privacy settings, the circle turns blue and your life becomes open to the world.
All this is now two years out of date. I hate to think how much bluer the circle has become in the intervening time.