On the Internet, viral marketing is any marketing technique that induces Web sites or users to pass on a marketing message to other sites or users, creating a potentially exponential growth in the message's visibility and effect. One example of successful viral marketing is Hotmail, a company, now owned by Microsoft, that promotes its service and its own advertisers' messages in every user's e-mail notes.
Some marketing people prefer terms other than viral marketing. In his popular e-mail newsletter about selling on the Web, John Audette asked readers to suggest alternatives, including other terms in current use. Among those suggested have been:
cascading style marketing
grass roots marketing
referral marketing (borrowing a term long used in marketing prior to the Web)
One reader suggested word of mouse.