Agitprop is a combination of the words agitation and propaganda, and came into use in Soviet Russia, where a Department of Agitation and Propaganda was an essential wing of the government. The term is frequently used to describe theater, literature, and music designed to encourage people to be more active and better understand communist beliefs. In more recent times, "agitprop" may be used to describe any form of mass media that tries — often through the use of emotionally loaded language — to influence public opinion.
The word "agitprop" was not originally meant as a negative term, although it has taken on that connotation. The word agitatsiya or "agitation" can translate as stirring someone to action, which could also be called activism. Propaganda further meant to spread information, and is not associated with the more negative definitions given it today.
Before the invention of the word, agitprop was already a common thing. For instance, the impetus behind American involvement in World War I really came down to the sinking of the Lusitania, a luxury ship that was torpedoed by a German submarine. Prior to that, President Woodrow Wilson had spent significant time trying to find a peaceful solution to the war in Europe and to prevent American involvement. Public sentiment changed, and people were stirred to action by what was viewed as German indifference.
Stories of the Lusitania's destruction were featured in virtually every newspaper across the US, creating agitation, and information about the sinking, the propaganda part, wasn't hard to find. In particular, the deaths of women and children were stressed, creating greater demonization of the German people. It is not that this may not have been deserved, and for those European countries attacked by Germany, this is not even questioned.
Similarly, information disseminated right after the 9/11 attack in New York City was in essence agitprop. Certainly it was necessary to report the attack, to explain the situation, and to grieve over the loss of many lives. Some news stations were criticized for producing agitprop, however, since they played footage of the attack repeatedly and inserted commentary. This stirred Americans greatly, and without minimizing the devastating effects of the attack, it can be said the attack made it quite easy for the country to almost immediately sanction war in Afghanistan. The agitprop that followed focused not only on 9/11, but also on the evils of the Taliban, their oppression of women, and their harboring of terrorists.
Governments may use agitprop with either good or bad intent to influence the people. For instance, in the 2000s, concerns about the health cost of America has led to numerous public reports about the effects of obesity, since it is the case that people who are obese may have greater health problems. Some of these reports are completely altruistic, designed to help Americans make better diet choices. Grim information disseminated specifically by the government, or by the media, is meant to stir people to action and to educate them, in the hopes that people will lose weight. Some question the motives, however, and point to greater discrimination of overweight people as part of this type of agitprop.