Final answer:
The introduction serves to establish the topic, provide background information, and present the thesis statement, guiding both the reader and the writer through the main points of the paper.
Step-by-step explanation:
The purpose of an introduction in developing the main idea is manifold. Foremost, it establishes the topic or issue at hand, providing essential background information to set the scene for the readers.
A well-crafted introduction acts as a roadmap, not only for the reader but also for the writer, indicating the thesis statement and the main sub-points that will be developed in the subsequent body paragraphs. By providing this structure, the introduction ensures that the audience is engaged and aware of the direction the argument will take, making the paper easier to follow and the argument more persuasive.