Ethos is a speaker's way of convincing the audience that she is a credible source.
An audience will consider a speaker credible if she seems trustworthy, reliable, and sincere.
This can be done in many ways. For example, a speaker can develop ethos by explaining how much
experience or education she has in the field. After all, you would be more likely to listen to advice
about how to take care of your teeth from a dentist than a firefighter. A speaker can also create ethos
by convincing the audience that she is a good person who has their best interests at heart. If an audience
cannot trust you, you will not be able to persuade them.