Citizen journalism represents a rich phenomenon, based on information content generated and shared online by nonprofessional journalists. It has allowed an increase in the degrees of freedom on the part of audiences in the experience and practice of use of news, giving them the opportunity to set up an alternative agenda than that proposed by mainstream media. In several occasions such as the World Trade Center terrorist attacks (2001), Indian Ocean tsunami (2004), London subway bombing (2005), and Hudson River landing (2009), the work carried out by amateur journalists has been precious and has enriched the content transmitted by traditional media. The entry examines the pro and cons of the phenomenon, illustrating its impact on news production, and outlining possible future research directions.