When you observe people around you some of them will talk fluently when there are limited people around you. But the same people will talk nothing when the person is in front of huge crowd or in front of the people those who are not known to him. These are all because of lack of speaking skills and they will feel themselves as inferior. The most common reason that you have heard from such people is they will fell that the words or the matter that they are going to convey might wrong and they will think that what the people will think about the words that the person was speaking. Some people get nervous when the person is asked to speak something about one topic in front of huge crowds. Basically they will deliver the better speech when they are surrounded by limited number if people or when they are with closed ones. For such people they need public speaking training where they will teach about various things and how to deal all the situations that would encounter while speaking in the public.
There are some points that you need to consider while speaking in the public. As you are talking to huge crowd there are lots of categories of people that may like your words or that may not like your words. So if you are planning to speak some thing publicly then the speech would be in such a way that it has to convince everyone around there. The speech that you have given will have to make impact on them and the thinking of the people has to change after listening your words. There should be no lies in the speech that you have spoken because if they found that the words that have spoken by you are false then they won’t listen your words next time. While speaking on the public you have to be precise on what your speaking, this will enable to the audience to listen more with interest. Explanation with some examples that has happened previously will bring a lots of change in your speech and people will start following you because if the motivation that they got from your speech. Speak in the limits and the words that you have spoken will have to create a lot of impact.
Hope the above information will give a clarity on what all things that have to discuss.