They provide background information to give readers some context about the topic. They should "build" towards the thesis statement.
It is the most important sentence in the entire essay because it presents the essay topic, the writer's position on that topic and the main ideas that will be discussed in the body paragraphs.
The first sentence of a body paragraph expresses the topic of the paragraph and provides a controlling idea about the topic. All information in the paragraph supports the controlling idea.
At the start of the conclusion, the thesis is restated in words different from those in the introduction.
They explain and develop the topic sentence. They present logical thoughts, evidence, and explanations in support of the controlling idea.
The main ideas from each of the body paragraphs are summarized as a reminder to the reader.
The writer ends the essay by presenting a final thought on the topic – for example, by stating an opinion, a solution, or a prediction. The final thought should leave a strong impression and encourage the reader to think further about the topic.
The paragraph may end with a concluding thought on the paragraph topic. It may also show a transition to the next paragraph.
The first sentence (or sentences) of an essay should catch the reader’s attention. It introduces the topic of the essay in an interesting way.