The author mentioned facebook being the most popular internet site in the world. With companies like facebook and google which are extremely useful and very widely utilized by the world, and are also free to use, then you become not the customer of those sites but the products. The way these companies turn a profit is by selling your data, that they have amassed plenty of by y0u using their services, to advertisers. This has become increasingly apparent in the past month when it was discovered that this data mining by advertisers was used to influence the 2016 US presidential elections. This is the problem, when it is this easy to collect data in our digital age, especially data about people, we lose privacy.