The terrorist blast had destroyed the office building. Piles of glass and concrete littered most of city block, the air was thick with dust, debris still smoldered. The police had no suspects but had already sent out an all-points alert. Then when troopers pulled a van over for making a couple of risky lane changes, they found a duffel bag held a change of clothes, a small kit with a new razor and other toiletries, and a .45-caliber pistol. The truck had been stolen, and the driver wasn't talking. Within an hour, an FBI team walked into a Wal-Mart with the picture of the arrested man. One of the cashier recognized the face, she said, "He lives out on county 15". The clue for the FBI was the razor blade the suspect bought from the Wal-Mart, which had a unique identification code to be tracked down - This may should like the start of a mediocre TV drama. But given recent events-and coming technical advances- it just might be a scenario pulled from tomorrow's news. The fact is that, they know where you are- but the question is do they have the right to know that? They know what you are doing- but do they need to know this? They know whom are you talking to- but what help can they provide knowing all these? As to improve security all of these have already been done; putting tracking devices, tracing phone calls, placing security cameras, providing biometrics identification etc. but with the price of privacy for sure. Privacy is moving to the top of the public agenda right now. If you talk to a person with a topic of security of recent days, you won't need to wait more than a minute to come up with another topic - privacy. I choose to explore and research this relationship between 'privacy and security' because I think this issue can affect my personal life as well as others. In this civilized world, no one is going to sacrifice his/her privacy. But when the question of security arrives, the question of compromise also arrives.