What key elements should be present in an introductory paragraph?

The most important element of an introductory paragraph is the thesis statement, in which the writer puts forth the basic claim of the essay and the conclusion that can be drawn from that claim. The thesis statement is generally a single sentence.

Other elements that should be present in the introductory paragraph include a brief introduction to the topic of the essay, including why it is important or interesting. The introduction to an essay should also include a brief discussion of methodology or structure that explains how the writer plans to address the topic and by what means he plans to prove his thesis.