Another use for a VPN is if one is downloading content that one does not want others to know about. This may be legal or illegal content. Either way, a VPN ensures absolute anonymity. However, the most important reasons to use a VPN, as far as this book is concerned, is the level of privacy that it affords.
For more information about VPN’s, the TorVPN website is particularly useful in explaining complicated concepts in easy- to-understand language.