2. Wi-Fi

The radio waves produced from your laptop's Wi-Fi card and the router travel to infinity.

If your wireless internet router is still configured as 'unsecured' or uses the 20 year old WEP encryption, then your data can easily be read by eavesdroppers. The encryption you choose on the router should not be confused with the encryption between the website and your browser, which is depicted by a padlock icon or a special horizontal bar when Firefox and Chrome approves of the banking site.

Since these radio waves are all over the place, it would be difficult but not impossible to record information with packet sniffers and cycle through millions of keys to find one that decrypts all the data. 512 bit and even 660 bit RSA keys have been broken recently by the University of Bonn in Germany.

For extra security, or if you have suspicions over someone in your neighbourhood, you could plug the laptop directly into the ethernet port at the back of the router to keep your banking data from going over the air.