It is used to show the results of something over a period of time such as days, weeks, months and so on.
A line graph is useful for showing trends or continuous change. Other kinds of graph also will show these, but a line graph is usually clearest.
line graph
line graph
line graph
Line Graph
Line Graph
sht up
Line Graph
Line Graph
For comparison purposes, a multiple line graph would be best.
I believe that this would probably be a line graph, or a double line graph-whichever you choose to call it. It could also be a double bar graph though too.
if you are graphing a change over time, a line graph. if you are comparing data, it's a bar graph.