"Close Application" refers to the process of shutting down a software program or app that is currently running on a device. This action can be performed through various methods, such as clicking the "X" button in the corner of the application window or selecting "Close" from the menu. Closing an application helps free up system resources and can improve device performance. When a user chooses to close an application, any unsaved work may be lost unless it has been saved prior to closing. Some applications, like Microsoft Word or Adobe Photoshop, may prompt users to save their work before exiting to prevent data loss.