Rhetoric may refer to discourse—spoken or written, usually dealing with persuasion and argument. Rhetoric may also be non-discursive in terms of visuals. (ask Derek more about non-discursive rhetoric...I’m somewhat familiar with Burke’s terministic screen, but that doesn’t necessarily directly relate to visual rhetoric).
The art of Rhetoric traces back to as far as the….how much history should I give? Rhetoric can more recently be traced to the 19th century philosopher, Aristotle, who defines Rhetoric as "the faculty of observing in any given case the available means of persuasion.” Say more here. Introduce ethos, pathos, and logos.
Ethos: ethical appeals based on character, credibility, and reliability. In rhetoric, ethos are used as a mode of persuasion, and a rhetor’s ethos needs to be established from the start. For example, if a mayoral candidate is trying to convince the public that he/she is credible and should be re-elected, they will try to establish their ethos by saying what positive contributions they have made to the community, how they support the education of children, and why they are qualified for the position.
Pathos: appeals to an audience’s needs, values, and emotional sensibilities. Similar to "ethos", in rhetoric, "pathos" is also a mode of persuasion, but this mode focuses particularly on appealing to an audience through emotion so as to “induce them to make the judgment desired.” For example, to convince us the dangers of second-hand smoke, an advertising company might show pictures of sickly children coughing in a dark room surrounded by smoke in order to make us feel guilty or bad for making children suffer.
Logos: appeal to reason that relies on logic or reason. Often depends on the use of inductive or reductive reasoning “Originally logos referred to the actual content of the speech and how it was organized.”