@qaarjk
Dear i dont have enough time to explain why outline is important in essay and will only say that its very very important.Its helps you arranging your ideas in desired order. Once put down successively it helps you to concentrate on other things like grammar and spellings as you have already evolved ideas in the form of outline.And you dont need brainstorming for ideas. You write continuously and consistensely without pressurising your mind. I intend to give outline in every paper and in every question.................Its your outline which casts the lasting impression on examiner.
hope it helps....

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Whatever mind can conceive,it can achieve - W.Clement Stone