Guerrilla marketing is an unconventional advertising strategy designed for small businesses with limited budgets. It involves promoting products or services in public places like streets, shopping centers, parks, and beaches to attract large audiences. Some examples of guerrilla marketing campaigns include PETA promoting animal rights in public areas in 2012, Panasonic promoting its prestige line at the 2002 FIFA World Cup, and Victoria's Secret sponsoring a Pac-Man game in a GameStop store.