And, it is not necessary to point out or add headings telling readers what parts of the article are "introduction, body, and conclusion." For example, I see a lot of writers especially subheading their concluding paragraphs with "To Conclude" or "Conclusion" – your conclusion should be apparent in the summing of your article without talking down to the reader by pointing it out.

Your writing should flow from intro, through body, to your conclusion without naming them.