We call it... knowledge

Do you know? Introduction and conclusion are the most important part of a speech. Your introduction is your first impression, and it sets the audience's view about whether the speech will be interesting, relevant, smart, or opposite. While the conclusion shapes the audience's memory of the speech. The introduction is written after the preparation and writing of the body paragraphs. Completing the body first can help generate original ideas for the introductory paragraph. An introduction is generally about 10 percent of the length of the entire speech, so for a five-minute speech, introduction of about thirty seconds is appropriate.  

So, please avoid it to be like this.