Your privacy is constantly in danger: Whether you share your computer or are using a laptop. Whether you have confidential data on your hard drive or use a USB stick to transport data. Whether your PC is being repaired or to be sold and you would like to clean up your hard drive.
You leave traces online and offline: The acquisitiveness of today's programs has no limits.
Passwords can be a real security threat: When they are easy to guess. But who can actually remember secure thus complicated passwords?
E-mails can easier be read than post cards. However, many times confidential information is sent out via e-mail anyway as it seems bothersome to use complicated encryption technology.