set tabstop 4 code example

Example: how to enable 4 space tab on vim

set tabstop=4       " The width of a TAB is set to 4.
                    " Still it is a \t. It is just that
                    " Vim will interpret it to be having
                    " a width of 4.
set shiftwidth=4    " Indents will have a width of 4.
set softtabstop=4   " Sets the number of columns for a TAB.
set expandtab       " Expand TABs to spaces.
filetype plugin indent on " Use filetype detection and file-based automatic indenting.

Source: Stackoverflow.com 
Author: Shervin Emami.