So you can tailor the speech to fit the audience. I once was with a group of volunteers at a conference and during one of our meeting a speaker was brought in to address the group. The topic she chose was the virtues and benefits of volunteering. It was a persuasive speech intended to persuade volunteers into volunteering, and therefore the speech was a waste of time. Both for her to give the speech and for us volunteers to listen to it. Had she known her audience was a group of volunteers she might have written a speech that was more appropriate to her audience. Some factors you need to be aware of regarding your audience are age, education level, maturity, interests, the setting of the audience, and the motivations of the audience. For example if you were to give a persuasive speech about benefits of kosher butcher techniques to a bunch of butchers is one thing. It would be another to give the same speech at a PETA convention. Does this make sense?