The following figure illustrates another tic style available in gnuplot, where the tics stick out of the plot rather than intrude on the interior of the graph:
This style is useful when inner tic marks might obscure your plot elements, for example, when part of the curve lies close to an axis.
Following is the script used to obtain the previous figure:
set tics out set grid plot [-3:3] tanh(x)
The new command here is the first line, which leaves everything else the same while drawing the tics so that they stick out of the borders.