Ethos is one of the three modes of persuasion as defined by Aristotle.
Ethos is the appeal to the authority, character, and trustworthiness of the communicator to persuade the audience.
Its purpose is to establish the speaker or writer as credible, knowledgeable, and reliable. Therefore, building trust and goodwill within the audience. Thus, making the argument of the writer or speaker more convincing, as expertise or high moral character had previously been demonstrated.
To establish ethos, the communicator ought to show knowledge and expertise on the topic at hand. Furthermore, honesty, integrity, and fairness should be demonstrated.
The communicator should be using a professional tone and proper language while citing reputable sources.