Why is an outline essential to any type of writing?

Outlines are an invaluable tool for many forms of communications. For a speech, however, it can be crucial. When speaking, it is imperative to keep your focus and to keep your aucience interested. An outline can do both of these things. A good outline will help you touch on all the major points of your speech as well as the supportive information. It can also keep you focused on the initial point or points of your speech. Finally, when you have a good outline you can see the flow of the speech. Is it flowing nicely? Is it consistent with the point you need to make? Is it too long or too short?