There are two kinds of bar graphs, vertical and horizontal, and they are useful when displaying evolution, deviation, ranking, comparison, structure or composition.
Avoid pattern lines and borders and use distinct colors. It´s better to skip the grid lines in most cases where there are areas in the graph that are not covered by bars, but still would display grid lines. Grid lines could be a very helpful visual tool if they only cut through the bars and not the graph area.
When displaying ranking, use horizontal bar graphs.
The best practice principles are:
- Use horizontal labels on both the x- and the y-axis as vertical or tilted text is difficult to read.
- Start the y-axis at zero value, as other values do not reflect the truth.
- The distance between bars should be half or slightly less than the width of a bar.
- Use the same color for the bars unless you a) want to highlight an exception, b) want to distinguish a group from others, or c) are using a bullet graph.
- Order your data so that they make sense and are not random.
Below are some examples: