There are far more types of audiences than there are types of presentations because audiences are made up of people and people come in innumerable flavors. Individuals could be invited to speak to groups all across the country. What the individual says and how they may say it depends on the makeup of those groups. They may ask you the individual to address a room full of factory operations managers who have no choice but to attend their talk, you they may go before a congressional committee looking into various environmental issues. When an individual stands up to deliver a presentation before an audience, its essential that the audience know who the presenter is, why they are there, what specifically they expect to get from your presentation, and how they will react to your message. You wont always be able to determine these factors, but you should try to gather as much background information as possible before your presentation. There will be times, especially with presentations that are open to the public, when you will only be able to guess.