The most compelling speeches are those in which the speaker doesn’t engage and interacts with his or her audience.

Your audience will use your verbal cues to more fully comprehend your message and will often connect with or disengage from your message based on those cues.

Your verbal interaction with your audience consists largely of body language cues.

Interaction is not important in public speaking because it does not involve your audience being more directly with both you as speaker and your content. 

Grammar and punctuation are characteristics of written language.

Another great way of engaging with your audience is both acknowledging them at the beginning of your speech and then thanking them for their  time and attention at the conclusion of your speech.

The speaker should engage the audience by interacting with them instead of just speaking to them.

An involved and engaged audience is more likely to pay attention to you and connect with your words.

Signals are anything that serves to indicate, warn, direct, command, or the like, as a light, a gesture, an act, etc.