With Custom Shows you can create a separate show, aside from the main presentation to present to a particular audience. The two kinds of Custom Shows that PowerPoint provides are Basic custom shows and Linked custom shows. With the Basic show you can pick which slides to show to which audience, in other words you can divide the presentation. With the Linked show you can add a separate slide show to the original presentation. It is especially useful when you have two separate audiences, viewing the presentation for different reasons. Once the general presentation is finished the two separate links will begin with information pertaining to each audience.