What is the purpose of introducing paragraphs when writing an essay

It gives the reader some background information about your topic.

Explanation:

If the reader isn't properly introduced to your writing, they may not be interested, or feel suprised when one immediatly launches into their first paragraph. The introduction tells why you have written the paper and what the reader should understand about your topic and your perspective, or what to know before stating your thesis. Think of it like a courtesy to your reader; a necessary courtesy.

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