Rhetoric is the art of discourse, an art that aims to improve the capability of writers or speakers that attempt to inform, persuade, or motivate particular audiences in specific situations. As a subject of formal study and a productive civic practice, rhetoric has played a central role in the Western tradition. Its best known definition comes from Aristotle, who considers it a counterpart of both logic and politics, and calls it "the faculty of observing in any given case the available means of persuasion." Rhetorics typically provide heuristics for understanding, discovering, and developing arguments for particular situations, such as Aristotle's three persuasive audience appeals, logos, pathos, and ethos. The five canons of rhetoric, which trace the traditional tasks in designing a persuasive speech, were first codified in classical Rome: invention, arrangement, style, memory, and delivery. Along with grammar and logic (or dialectic—see Martianus Capella), rhetoric is one of the three ancient arts of discourse.
From ancient Greece to the late 19th century, it was a central part of Western education, filling the need to train public speakers and writers to move audiences to action with arguments. The word is derived from the Greek ῥητορικός (rhētorikós), "oratorical", from ῥήτωρ (rhḗtōr), "public speaker", related to ῥῆμα (rhêma), "that which is said or spoken, word, saying", and ultimately derived from the verb ἐρῶ (erō), "say, speak"