When off a buffer is unloaded when it is |abandon|ed. When on a buffer becomes hidden when it is |abandon|ed. If the buffer is still displayed in another window, it does not become hidden, of course. The commands that move through the buffer list sometimes make a buffer hidden although the 'hidden' option is off: When the buffer is modified, 'autowrite' is off or writing is not possible, and the '!' flag was used. See also |windows.txt|. To only make one buffer hidden use the 'bufhidden' option. This option is set for one command with ":hide {command}" |:hide|. WARNING: It's easy to forget that you have changes in hidden buffers. Think twice when using ":q!" or ":qa!".