The CNN effect is a theory in political science and media studies that postulates that the development of the popular 24-hour international television news channel known as Cable News Network, or CNN, had a major impact on the conduct of states' foreign policy in the late Cold War period and that CNN and its subsequent industry competitors have had a similar impact in the post-Cold War era. While the free press has, in its role as the "Fourth Estate," always had an influence on policy-making in representative democracies, proponents of the CNN effect argue that the extent, depth, and speed of the new global media have created a new species of effects qualitatively different from those that preceded them historically.  The term's coinage reflects the pioneering role played by the network CNN in the field, whose "saturation coverage" of events like the Tiananmen Square protests of 1989, the fall of Communism in eastern Europe, the first Gulf War, and the Battle of Mogadishu was viewed as being strongly influential in bringing images and issues to the immediate forefront of American political consciousness and beyond. Despite these origins, the term as used generally refers to a broad range of real time modern media, and is not exclusive to CNN or even 24-hour news cycle broadcast cable news.
In his research paper Clarifying the CNN Effect: An examination of Media Effects According to Type of Military Intervention, George Washington University professor Steven Livingston identifies three distinct aspects that fall under the broad term of the CNN effect. The media may function alternately or simultaneously as
(1) a policy agenda-setting agent, (2) an impediment to the achievement of desired policy goals, and (3) an accelerant to policy decisionmaking. (Italics in original) 
By focusing instantaneous and ongoing media coverage on a particular conflict, international incident, or diplomatic initiative, the news cycle effectively demands political attention, as governing politicians attempt to demonstrate that they are "on top of" current issues. The effect has been, according to Margaret Belknap, that "[t]he advent of real time news coverage has led to immediate public awareness and scrutiny of strategic decisions and military operations as they unfold"  Deeper penetration and wider broadcast of statements and actions by public figures may increase transparency, but it can also complicate sensitive diplomatic relationships between states or force an official reaction from governments that would otherwise prefer to minimize political risk by remaining noncommittal. The information revolution and spread of global mass media through the Internet and international 24-hour news thus accelerates the policy-making process, requiring a faster tempo of decision and action to forestall the appearance of a leadership vacuum.
Former Secretary of State James Baker said of the CNN effect "The one thing it does, is to drive policymakers to have a policy position. I would have to articulate it very quickly. You are in real-time mode. You don't have time to reflect." His former press secretary, Margaret Tutwiler, mirrors his sentiment: "Time for reaction is compressed. Analysis and intelligence gathering is out."
Natural Disasters and the "CNN Effect" 
While the "CNN effect" most commonly refers to the effect that news media have on politics and government during political conflict, its effect on decisions made during natural disasters is also noteworthy. As videos and images are broadcast worldwide immediately after or even during natural disasters, these images may convince the public to donate money or pressure governments for immediate action.
The "CNN effect" may have played a role in increasing aid following the Asian tsunami (2004), the Kashmir earthquake (2005), Hurricane Katrina (2005), and the Sichuan earthquake in China (2008). Following the Asian tsunami, for instance, the media "blitz" that followed this natural disaster may have helped prompt an unprecedented outpouring of donations. "By February 2005, the international community had donated $500 per person affected by the tsunami, compared to just 50 cents for each person affected by Uganda’s 18-year war."
See also 
- Al Jazeera effect
- Broadcast journalism
- Local news
- News broadcasting
- Media circus
- Media event
- Media scrum
- Missing white woman syndrome
- News program
- Nineteen Eighty-Four (a dystopian novel by George Orwell)
- Slashdot effect
- Television news
- Television program
- Trial by media
- Yellow journalism
- Livingston, Steven. Clarifying the CNN Effect: An Examination of Media Effects According to Type of Military Intervention(PDF). John F. Kennedy School of Government's Joan Shorenstein Center on the Press, Politics and Public Policy at Harvard University. 1997.
- Belknap, Margaret H. The CNN Effect: Strategic Enabler or Operational Risk? (PDF). U.S. Army War College Strategy Research Project. 2001.
- Shah, Anup. Media and Natural Disasters. Globalissues.org. 23 Oct. 2005.
- "CNN effect" is Not Clear-Cut, essay by Indiana University School of Law professor Fred H. Cate, in Humanitarian Affairs Review. 2002.
- "The CNN Effect": How 24-Hour News Coverage Affects Government Decisions and Public Opinion, Brookings Institute/Harvard University forum transcript. 2002.
- The "CNN Effect:" TV and Foreign Policy, Center for Defense Information America's Defense Monitor transcript. 1995.