"If the online service is free then you are the product," techies say. Google and Facebook make a fortune by collecting personal information, which helps them target their advertisements more accurately. Free smartphone apps typically suck in all the data they can, such as the person’s location or their entire address book. At the same time, governments collect lots of information about everyone, not only through mass surveillance, as the disclosures made by Edward Snowden, but also by gathering common things, such as voter registration and driving-licence records that are then sold on to commercial firms.
More than ever, individual privacy is under threat. Julia Angwin, who oversaw a pioneering series of Wall Street Journal articles called "What They Know", started in 2010, exposes many of the questionable activities that erode privacy—activities that most people know nothing about. Hundreds of unregulated data-brokers exist in America, for example, selling dossiers on people to marketing companies. Individuals have little recourse if they want to examine their files or correct mistakes. One company runs a fleet of camer-aequipped cars that scan the number plates of 1 million vehicles a month, mostly to find those wanted for repossession (收回)—but it sells the data to insurers or private investigators as well.
Ms Angwin decries this shadowy business. Her book tracks her attempts to wrest freedom from it. She gets a credit card using an alias; she uses an anonymous search engine and encrypts (加密) her e-mail and texts; she leaves LinkedIn. When she turns off basic web-browsing functions that enable tracking (using so-called cookies) she becomes digitally paralysed. Amazon items appear to be out of stock and she is unable to set up an appointment at an Apple store. "My daughter would stand next to me and laugh while I tried to load a page and navigate through all the permissions," she writes.
Yet "Dragnet (搜索网) Nation" has its faults. It ignores how exciting the legitimate uses of personal data can be to companies, governments and NGOs. It mixes state surveillance (监控) and privacy-eroding business practices, weakening the study of both. Ms Angwin’s analysis of the problems and potential regulatory remedies is shallow, and her attempts to escape the dragnet eventually become wearisome. Her contribution is to have made herself a guinea pig in an experiment to avoid ubiquitous surveillance. But the real story about the economy of personal information and protecting privacy in an age of big data has yet to be written. What can we learn from the second paragraph