The conclusion is written in one paragraph and its main purpose is to sum up the arguments of the essay, which the author revealed in the topic sentences of the body paragraphs. It summarizes the evidence in support for the thesis statement of the essay and if proved restates this statement. It is a final glance at the presented facts, which lead to a certain conclusion on the essay matter.
The conclusion does not have a set structure and can be written according to the peculiarities of the essay but must always have the mentioned above argument summary analysis.
Never apologize for or otherwise undercut the argument you've made or leave your readers with the sense that "this is just little ol' me talking." Leave your readers with the sense that they've been in the company of someone who knows what he or she is doing. Also, if you promised in the introduction that you were going to cover four points and you covered only two (because you couldn't find enough information or you took too long with the first two or you got tired), don't try to cram those last two points into your final paragraph. The "rush job" will be all too apparent. Instead, revise your introduction or take the time to do justice to these other points.