With a rather large, all-encompassing definition, stealth marketing can describe many different types of internet marketing campaigns. The marketing term (aka undercover marketing, buzz marketing or guerrilla marketing) describes any marketing tactic used to appeal to consumers, when the buyers do not know they are being targeted.
In this sense of the definition, stealth marketing can be used in crowded marketplaces, television shows, or any other form of entertainment where marketing is not suspected. So, for example, when a movie-goer is watching a scene in a grocery store, the product placement of the Coca Cola on the shelf behind the main actor is a stealthy move for Coke to advertise without the consumer's expectation.