Guerrilla marketing uses unconventional and low-cost tactics like graffiti, stickers, and flyers to locally promote ideas, products, or services. While guerrilla marketing is one marketing strategy, it does not guarantee success. The examples provided show how brands like Cadbury, Nike, KitKat, and others have effectively used unexpected guerrilla tactics that tell stories with humor to go viral without relying on social media. The document encourages finding the best explanatory infographic image to further illustrate guerrilla marketing techniques.