Almost everything you do in the IDE is contained within the scope of a project. The project represents the software you are working on—it is the top-level container for all your modules, libraries, and configuration settings. There can be only one project open in a single IDE window. If you would like to have multiple projects open, IntelliJ IDEA will open them in separate, isolated windows. You can switch between the windows using the Next Project Window or Previous Project Window options from the Window menu or using the keyboard shortcut, Ctrl + Alt + open/close bracket.

IntelliJ IDEA stores the project's configuration in two different formats. The project's format is covered later in the Project format section.