According to Aristotle, rhetoric is "the ability, in each particular case, to see the available means of persuasion." There are three main forms of rhetoric: Ethos, Logos and Pathos. .
Aristotle defined ethos as the sense of credibility or trustworthiness that an author establishes in his or her writing. Derived from the word ethics ethos is a form of persuasion using credibility as its basis. An example of this is using a hot former porn star, Anna Nicole Smith to sell "Trimspa". She lost an enormous amount of weight on the drug and as a result has enough "credibility" and authority to convince the audience that the product really works.
Logos, however, "appeals to patterns, conventions, and modes of reasoning that the audience finds convincing and persuasive". The word Logos is derived from logic which in turn is the use of data and testimony to persuade the audience.
On the other hand Pathos seek to change the attitude of the audience by playing on feeling or emotion. Pathos can also be called pathetic. Pathos use sympathy and emotion in their arguments to move the audience. This ultimately gets the emotional support of the audience. .
These three types of persuasion by Aristotle can be most effectively used when used all together. Convincing the audience either, "as a sensible, moral man of good will (ethos). Or appeal to the character or mental state of the audience (pathos). Or, argue from the subject matter (logos) by using the inductive logic of examples and the deductive logic of enthymemes" (Lindemann, Erika. "What Do Teachers need to know about Rhetoric." A Rhetoric for Writing Teachers. 2nd ed. 38). In conclusion logos, pathos and ethos work in concert to help the author persuade the audience.