Your grandkids won't know what cash is

Physical metal and paper will eventually go the way of the Dodo. As electronic forms of payment become more popular, cash will be slowly retired from the international economic system. In many parts of the world, people already use their mobile phones as their wallets, carrying their ID (PDF) and money digitally.

In London as well as other cities, subway passengers can purchase their tickets by waving their phones in front of a scanner. Speaking of London, the city aims to make the 2012 Olympics held there cash-free. A single card will contain a visitor's funds for use at the stadiums and restaurants.

Although there are many arguments for the convenience and efficiency of electronic money, there are always privacy concerns. Electronic transactions are much simpler to track, and as the databases of these transactions grow and become increasingly interlinked with marketers' databases, we can expect more companies to know what we buy and where we buy it.