"Normally what I'm doing isn't some state secret or something confidential, but what if you are doing something like that? Then you really don't want people to see what you're doing do you? If you're in an airport or coffee shop with lots of people, it's very easy for people to see what you're doing if they really want to. 3M has come out with a Privacy Filter called the Vikuiti for just such occasions, it can be used on your laptop or on a standard LCD or CRT display. It's very easy to install, lightweight and it works very well..."