Answer:
The principle purpose of the introduction is to present your position (this is also known as the "thesis" or "argument") on the issue at hand but effective introductory paragraphs are so much more than that. Before you even get to this thesis statement, for example, the essay should begin with a "hook" that grabs the reader’s attention and makes them want to read on. Examples of effective hooks include relevant quotations ("no man is an island") or surprising statistics ("three out of four doctors report that…").
Only then, with the reader’s attention "hooked," should you move on to the thesis. The thesis should be a clear, one-sentence explanation of your position that leaves no doubt in the reader’s mind about which side you are on from the beginning of your essay.
Following the thesis, you should provide a mini-outline which previews the examples you will use to support your thesis in the rest of the essay. Not only does this tell the reader what to expect in the paragraphs to come but it also gives them a clearer understanding of what the essay is about.
Finally, designing the last sentence in this way has the added benefit of seamlessly moving the reader to the first paragraph of the body of the paper. In this way we can see that the basic introduction does not need to be much more than three or four sentences in length. If yours is much longer you might want to consider editing it down a bit!
