The splash page is usually used in the first few pages of the comic and is used to tell a lot of different information. It is where the artist often draws us into the story with some kind of action, depicts the title of the issue, and is also where they put more information such as who the creative team behind the comic is as well as who publishes the comic book. At one time they used to put a white bar at the bottom with the fine print of the year the comic was published and other necessary information, but they stopped doing that a while back.
Splash pages are also used in other areas of comic books as well. Interior Splash Pages are used further on in the comic and usually depict the climax of the battle or action. Sometimes comic books have a splash page that covers two pages in which it is referred to as a Double Page Spread. Panels that take up most of the page and are larger than the other panels are often referred to as Splash Panels.
These devices and how they are used by artists are one of the reasons why the comic book is such a great medium. The splash page can be used in so many ways to enhance the story and bring the reader right into the action.
These pages are also much more sought after in the comic book art market and therefore fetch much higher prices.