Incivility is a general term for social behaviour lacking in civility or good manners, on a scale from rudeness or lack of respect for elders, to vandalism and hooliganism, through public drunkenness and threatening behaviour. The word "incivility" is derived from the Latin incivilis, meaning "not of a citizen".

The distinction between plain rudeness, and perceived incivility as threat, will depend on some notion of civility as structural to society; incivility as anything more ominous than bad manners is therefore dependent on appeal to notions like its antagonism to the complex concepts of civic virtue or civil society. It has become a contemporary political issue in a number of countries.

Civil behavior requires that people communicate with respect, restraint, and responsibility, and uncivil communication occurs when people fail to do so. Universal pragmatics, a term coined by Jürgen Habermas, suggests that human conflict arises from miscommunication, so communicative competence is needed to reduce conflict. Communication competence "involves the ability to communicate in such a way that: (1) the truth claim of an utterance is shared by both speaker and hearer; (2) the hearer is led to understand and accept the speaker’s intention; and (3) the speaker adapts to the hearer’s world view." If people disagree about the truth or appropriateness of their interaction, conflict will occur.

According to Habermas, we should establish communicative norms that lead to rational conversations by creating the social coordination needed for interactants to pursue their goals while recognizing the truth or appropriateness of their interaction. Such norms, or social rules, include: "all participants must be allowed to speak freely, all participants must be allowed to speak for themselves (to enable them to establish their own ethos or "selfhood"), and that communication should be equal, with no one participant commanding more attention from the others than is afforded to them on their turn."

Some examples of uncivil communication include rude gestures, vulgar language, interrupting, and loudly having private discussions in public spaces. Recent poll data suggests that Americans believe uncivil communication is a serious problem, and believe it has led to an increase in physical violence. The 2013 study on Civility in America: A Nationwide Survey, conducted by global public relations firm Weber Shandwick and public affairs firm Powell Tate in partnership with KRC Research found that 70 percent of Americans believe incivility has reached crisis proportions. Of those who expect civility to worsen, 34 percent blame Twitter. The study found that Americans encounter incivility, on average, 17.1 times per week, or 2.4 times per day. Some studies suggest that uncivil communication may have real consequences, including increased health problems due to stress, decreased work productivity, more auto accidents caused by aggressive driving, and vandalism.

Political incivility is different from the everyday incivility described above. According to face negotiation theory, politeness norms require us to avoid challenging others, but political incivility is different because, since it is specific to the political sphere, contestation of views and confrontation are required for a democracy to occur. According to Thomas Benson, "Where there is disagreement, there is a risk of incivility; in many cases, incivility is itself a tactic in political discourse, employed as an indicator of sincerity, as the marker of the high stakes in a disagreement."

Civil discourse is "the free and respectful exchange of different ideas". Eight out of 10 Americans believe that the lack of civil discourse in the political system is a serious problem. Eighty-two percent of American respondents to a 2011 survey felt that political advertisements were too "nasty" and 72 percent believed that political commercials that attacked the opponent were "inappropriate". Research has linked political incivility to reduced trust in the legitimacy of political candidates, political polarization, and policy gridlock. Campaigns and politicians are not the only avenues for incivility, however. The public also participates in civil discourse, and incivility. Incivility in these contexts can lead to the breakdown of political discourse, and exclude certain people or groups from the discussion. If people or groups are systematically excluded from the discussion, the democratic nature of that discussion is called into question.

In his article The Public Sphere: An Encyclopedia Article (1964), Habermas explains that the public sphere is "a realm of our social life in which something approaching public opinion can be formed… Although state authority is so to speak the executor of the political public sphere, it is not a part of it." Political incivility threatens the features of the rhetorical model of the public sphere, which include: