I have yaxis from 0 to 100. I want a grid line after every 10 units. How can I do that? That is, how can I draw grid lines after each 10 units?
The ytics variable controls how often or sparse the y scale values will be printed and thus the grid lines will be drawn.
set ytics 10 # y scale marks and values will be at every 10th unit
set grid # grid turned on at each scale values
replot # replot your graph
The mytics controls the minor marks on the y scale. The set grid mytics makes the y scale minor grid lines visible.