Media events can hold sway on many levels, from a small city television viewership up to the entire planet, sometimes occupying a smaller audience non-stop while a larger audience is fed sporadic updates. For instance, the dramatic twists and turns of Viktor Yushchenko's 2005 bid for the Ukrainian presidency, featuring poisoning plots, voter intimidation, outraged citizens demonstrating in the capital city and other tense, "newsworthy" developments, easily constituted an extensive media event within Ukraine itself even as international mass media followed it closely but did not grant it uninterrupted coverage. By contrast, the September 11, 2001 attacks did reach the plateau of a sustained, planet-wide media event, due mostly to the unprecedented realtime visuals, the involvement of citizens and perpetrators from many different countries and cultures, and a single-day intentional taking of human life not seen at such levels in the developed world since the end of World War II.
The coverage of global and national media events has become a pillar of large news organizations, which often operate at scant profitability in-between these major occurrences. Public opinion, and even baseline attitudes of one culture towards another, can be largely determined by what is seen and heard during a major media event, and the entire careers of journalists can be made (or un-made) by their conduct during these iconic situations. In the United States, the first full bore post-WWII media event was the 1963 assassination of President John F. Kennedy, and it, to a great extent, determined the unwritten hierarchy of American journalists and "news personalities" for the succeeding 40 years. The development of "glasnost" and the ensuing fall of Communism in Russia was a similar determinant for journalists there.
Parallel instances for almost every nation or region can be found, with the major media event corresponding to the shared memory of a "defining moment" often felt in personal, yet nationalistic, terms. The fall of the Berlin Wall in November, 1989 was such a moment for Germans on both sides; the resolution of the Chinese Civil War in 1950 still resounds in that nation; the achievement of independence from Great Britain in 1980 by Zimbabwe (formerly Rhodesia) was a defining moment which dominated news reporting on several continents at the time; the invasion, starting on March 20, 2003, that deposed Iraq's Saddam Hussein was one of the few modern media events capturing the attention of a majority of the planet's adults and will likely be commemorated in Iraq, in celebration or infamy, for generations, accompanied by news footage first transmitted that day. The distinguishing characteristic of all these is a day or other short period of time during which changes of great importance came to a head, lending themselves to breaking news-style media coverage.