An informative speech is one that informs the audience. However, as should be clear, this general definition demonstrates that there are many ways to inform an audience. Therefore, there are several types of informative speeches. The main types of informative speeches include definition, descriptive, explanatory, and demonstrative.
A definition speech explains the meaning, theory, or philosophy of a specific topic that the audience likely does not know much about. The topics may be general, such as a sport, or highly specific, like a particular person. The main goal of this speech is to educate the audience so that they understand the main points regarding this subject.
A demonstration speech explains how to do something. If you have ever sat through a lecture where a teacher explained how to create a bibliography, then you have heard a demonstration speech. Like most informative speeches, a how-to speech will likely use visual examples that show the audience how to move from step to step through a particular activity. Visualizations help the audience retain what each step looks like, increasing the likelihood that they will retain the overall information of the speech.
An explanatory speech might give a description of the state of a given topic. As an example, consider the types of speeches that are given at industry conferences. The goal of these speeches is for the speaker to inform the audience on a particular part of an industry. Commonly, these will also utilize visualizations that give the audience a visual representation of the particular data or statistics contained in the speech. This is one way to condense highly complex information into an easily retainable package for the audience.
A descriptive speech creates a vivid picture in a person's mind regarding an object, person, animal, or place. An archaeologist who has discovered a new temple in South America or a paleontologist who believes they have found a new dinosaur may use a descriptive speech to inform an interested audience about their recent discoveries .
As all of these types make clear, there are many ways that a given set of information can be communicated in a speech. When deciding what type of informative speech you want to write and deliver, consider what you want the audience to know about your topic.