Paragraph's first sentence usually states the main idea while the remaining sentences either support or explain it. Thus, the main idea is the thought that everything else in the paragraph or passage is there to support or illustrate. Main ideas should be simple and clear. They should also be accurate and informative. Try not to use too many words or phrases when writing about your own ideas because you want them to be easy to understand for the reader. Using simple language is always best when writing about scientific topics because scientists use complicated language to describe their work so that others can understand it. In addition to being simple and clear, the main idea must be relevant to the topic. If it isn't relevant, then it shouldn't be in the essay. For example, if the topic of the essay is "How I plan to change the world," then an idea that has no connection to the topic is irrelevant and shouldn't be included in the essay. Since becoming rich and famous has nothing to do with changing the world, it is not relevant information and should be removed from the essay.