The simple act of surrendering a telephone number to a store clerk may seem innocuous—so much so that many consumers do it with no questions asked. Yet that one action can set in motion a cascade of silent events, as that data point is acquired, analyzed, categorized, stored and sold over and over again. Future attacks on your privacy may come from anywhere, from anyone with money to purchase that phone number you surrendered. If you doubt the multiplier effect, consider your e-mail inbox. If it’s loaded with spam, it’s undoubtedly because at some point in time you unknowingly surrendered your e-mail to the wrong Web site.
Do you think your telephone number or address are handled differently A cottage industry of small companies with names you’ve probably never heard of—like Acxiom or Merlin—buy and sell your personal information the way other commodities like corn or cattle futures are bartered. You may think your cell phone is unlisted, but if you’ve ever ordered a pizza, it might not be. Merlin is one of many commercial data brokers that advertises sale of unlisted phone numbers compiled from various sources—including pizza delivery companies. These unintended, unpredictable consequences that flow from simple actions make privacy issues difficult to grasp, and grapple with.
In a larger sense, privacy also is often cast as a tale of "Big Brother"—the government is watching you or a big corporation is watching you. But privacy issues don’t necessarily involve large faceless institutions: A spouse takes a casual glance at her husband’s Blackberry, a co-worker looks at e-mail over your shoulder or a friend glances at a cell phone text message from the next seat on the bus. While very little of this is news to anyone—people are now well aware there are video cameras and Internet cookies everywhere—there is abundant evidence that people live their lives ignorant of the monitoring, assuming a mythical level of privacy. People write e-mails and type instant messages they never expect anyone to see. Just ask Mark Foley or even Bill Gates, whose e-mails were a cornerstone of the Justice Department’s antitrust case against Microsoft.
And polls and studies have repeatedly shown that Americans are indifferent to privacy concerns. The general defense for such indifference is summed up a single phrase: "I have nothing to hide. " If you have nothing to hide, why shouldn’t the government be able to peek at your phone records, your wife see your e-mail or a company send you junk mail It’s a powerful argument, one that privacy advocates spend considerable time discussing and strategizing over.
It is hard to deny, however, that people behave different when they’re being watched. And it is also impossible to deny that Americans are now being watched more than at any time in history.

The email example shows（）