The 5 paragraph essay is the normal form of presentation for college essays and has a set format which must be followed, staring with the first paragraph which is the introduction, followed by 4 supporting paragraphs with facts, quotes and statistical information which supports the thesis of the essay which appears in the introduction. Finally the conclusion paragraph restates but does not repeat the thesis in the introduction and summarizes the reasons supporting the thesis , perhaps with a final call to action at the end. No new facts must appear in the conclusion, which is the final justification of the thesis.
The second third and fourth paragraphs:
Each paragraph must be linked with a transitional word or phrase linking it to the previous paragraph. The must be a clear flowing and logical progression throughout the essay.
The five-paragraph format provides the means to write a logical progressive essay. The links between the paragraphs require careful thought so that they provide good links. The paragraphs lead on one from the other to arrive at the conclusion, which proves the thesis