E-mail marketing is a form of viral marketing. Viral marketing is widely used by large and successful companies as a means of advertising. Viral marketing is an excellent way to expand ones business.

Viral marketing is also called viral advertising. It is a means of using mouth-to-mouth communications like social networks to spread a company's or brand's message through the Internet or email.

Viral marketing, viral advertising, or marketing buzz are buzzwords referring to marketing techniques that use pre-existing social networking services and other technologies to try to produce increases in brand awareness or to achieve other marketing objectives (such as product sales) through self-replicating viral traffic.

This can be about ethicalness. For instance, was sony's viral marketing campaign on brooke fraser ethical?

Many marketing campaigns which go viral have something in their ads which seem to appeal to people. A funny or comical ad which one will remember will go viral before a plain one. A recent example is the K-Mart marketing campaign titled "Ship My Pants".