credibility

thumb|200px|Scientists with PhD degrees are considered credible sources in their field of expertise, due to their state-accredited advanced study. Credibility comprises the objective and subjective components of the believability of a source or message. Credibility is deemed essential in many fields to establish expertise. It plays a crucial role in journalism, teaching, science, medicine, business leadership, and social media.

Aristotle defines rhetoric as the ability to see what is possibly persuasive in every situation. He divided the means of persuasion into three categories, namely Ethos (the source's credibility), Pathos (the emotional or motivational appeals), and Logos (the logic used to support a claim), which he believed have the capacity to influence the receiver of a message. According to Aristotle, the term "Ethos" deals with the character of the speaker. The intent of the speaker is to appear credible. In fact, the speaker's ethos is a rhetorical strategy employed by an orator whose purpose is to "inspire trust in his audience".