What are the three things that every introduction must do in every type of essay?

1. Introduce the topic

2. Indicate how the topic is going to be developed (cause-effect, reasons, examples classification, description, narration, or explanation.) You writing purpose should be clear.

3. Contain a thesis statement / controlling idea ( for expository and persuasive.)

4. Be interesting and provide a "hook" to get the reader to want to read more.