In Greek the term 'ethos' means 'character'. It can be used to describe the character of an audience, nation or community. For example, one can speak of the 'American ethos' as the characteristics that define American culture. A US presidential candidate would have to speak to the ethos of this nation and culture in order to win votes.
Understanding ethos is important to understanding speech writing. As we study the rhetorical devices of speakers, we want to ask ourselves how the speaker appeals to the ethos of his or her audience. Texts often contain a sense of ethos in order to give the speaker more credit or authority on a matter.
In a sense, ethos answers the question: "What gives you a mandate to speak to me?" Examples of ethos can be found in the following text, 'Letter from Birmingham Jail' by Martin Luther King.