Number of columns of the screen. Normally this is set by the terminal initialization and does not have to be set by hand. Also see posix-screen-size. When Vim is running in the GUI or in a resizable window, setting this option will cause the window size to be changed. When you only want to use the size for the GUI, put the command in your gvimrc file. When you set this option and Vim is unable to change the physical number of columns of the display, the display may be messed up. For the GUI it is always possible and Vim limits the number of columns to what fits on the screen. You can use this command to get the widest window possible:

:set columns=9999

Minimum value is 12, maximum value is 10000.

(default 80 or terminal width)