How do body postures and gestures contribute in public speaking?

Body postures contribute greatly in public speaking, in order to receive the audience's undivided attention you should stand up straight with your shoulders back and look confident in what you're saying. If you're hunched over while you are speaking the audience won't think you really know what you're talking about. Hand gestures are also important to use, if you are just holding your hands behind your back or by your side the audience will become bored quite quickly, whereas if you use wide hand gestures and look like the topic doesn't bore you, it will be much more efficient at getting the point across.