Transitions are important in any type of communication, but they're even more essential to speaking than they are in writing. If you miss something in written material, you can always go back and reread. Haven't you ever found yourself reading along when you suddenly discover you're on a new topic, with no idea how you got there? So you turn back the page and try to re-establish the path the author took. Your audience can't rewind you when you're speaking live in front of them, so you have to make it as easy as possible for them to follow along.
As we've learned, speeches are made up of many parts that must fit well together. And transitions are responsible for much of that fitting: They take you from your opening into the body of your speech and provide a smooth passage between your main points, while also serving as smaller links between minor ideas. Yet transitions are so useful and frequent that they are often overlooked. If you hear a speaker stumble, chances are it's over a transition.