A Motion project contains a single composition made up of multiple image layers and applied effects. When you import still images and video clips into a project, Motion creates a linked reference to the source media files on disk but doesn’t move, duplicate, or modify the original files. Motion project files store information about how a composition is assembled, what media files on disk are used, and what effects from the Library have been applied. In addition to imported media, project files also contain shapes, masks, and text layers you create in the application.