The figure of the spy has been customary in film and literature. Types mysterious able to go anywhere unnoticed and extremely intelligent. Their mission: to collect information and send it. As a fictional character, are attractive, but it sure would not want to live forever with the suspicion that there is someone in your home, you can not see and is responsible to report on everything you do in your everyday life.
In the computer world this is what we call spyware (spyware), these are installed on our system in order to steal our data and spy our movements through the network. They then send that information to Internet advertising companies to market with our data. They work as ‘background’ so that we do not realize they are until they start to appear the first symptoms.