Viral marketing is a marketing strategy that encourages consumers to spread information about a company's goods or services via the internet. It inspires users to share messages with other users, leading to exponential growth. A classic example is Hotmail, which included promotional messages in every email, causing the service to spread rapidly among recipients. The rise of social media has increased the effectiveness of viral marketing, as users spend more time on social platforms than email. Both large and small businesses can benefit, but it is particularly well-suited to smaller companies seeking cost-effective growth.