Close

1. In general, close is an action performed to terminate a portion of a program or the complete program. If a file is being worked on or has changed since it has been opened and the program is closed, it is possible for the work done on that file to be lost.
2. When referring to a button or a feature in a GUI operating system, the close button allows a user to terminate a window within a program or the complete program.
   
   In Microsoft Windows operating systems and many other operating systems and software programs, the close button with a "X" is generally located in the top right corner of the window. If there are multiple windows opened within the program the "X" at the top right corner will close the program the "X" beneath will close the window but keep the program open. 
   
   In Apple Mac OSX operating system, the close button is represented as red button in the top right corner of the window.
   
   In the past and sometimes in the present close is used as another name for minimize.

Also see: Exit, Maximize, Minimize, Operating system definitions, Window