It sometimes happens in the workplace and at home that we need to leave your computer on. However we do not want another person has the ability to access the documents we are using or windows open while we are away. Shut off the computer is an option, but a little uncomfortable. If you have a USB memory, this task is made much simpler, using your pen drive as a USB key and the help of special software to protect the privacy of your computer. These programs, when installed on the computer gives our USB port locker status, or key, so the computer is blocked, unless it is inserted. These programs also serve to block MSN, mute the audio and many other tasks. The USB is an interface plug & play between the PC and certain devices such as keyboards, mice, printers, modems, sound cards, digital cameras, etc, which in the past were connected in a different way eg via serial or parallel ports , which require different drivers to function and there were a lot slower as far as transfer rate is concerned. This interface is also widely used in data storage devices such as the safety device or that our PC is locked and can not access our information as USB keys The work in this case as equivalent to the keys our home, to enter the house need our keys, to enter into the computer, USB memory, but not everyone, if not identified by computer via the unique identification number which has its pendrive. It will continue to serve for data storage, like any flash drive. And if you lose your key, anyway you can unlock the computer answering a security question, and “change the locks” by setting the use of a new one.