The conclusion serves two main purposes: 1) to signal to the audience that the speech is ending and 2) to reinforce the central idea of the speech. Effective conclusions use vocal cues like "in conclusion" to indicate the ending and build momentum so the ending is clear. The conclusion should summarize the main points, end with an impactful statement, and refer back to the introduction to give the speech unity. Speakers should prepare different potential conclusions and choose the one with the most impact.