Use this command to close all windows containing the active document. <<YourApp>> suggests that you save changes to your document before you close it. If you close a document without saving, you lose all changes made since the last time you saved it. Before closing an untitled document, <<YourApp>> displays the Save As dialog box and suggests that you name and save the document.
You can also close a document by using the Close icon on the document's window, as shown below: