Prosocial behavior online encompasses voluntary actions that benefit others or society. From early online communities to modern social media platforms, the internet has expanded opportunities for altruism, empathy, and collective action on a global scale. Key concepts include the online disinhibition effect, digital citizenship, and slacktivism. Psychological theories explain motivations behind online prosociality, while various digital platforms facilitate prosocial interactions. Factors influencing online prosocial behavior and real-world examples demonstrate its impact and challenges.