The most common type of bar graph (or bar chart) is a vertical bar graph. This type of graph displays data using vertical bars, with the height of each bar representing the value of the data being displayed. Horizontal bar graphs, on the other hand, display data using horizontal bars. A horizontal bar graph is often used when the category names are long or when the values being displayed are large, as the horizontal layout makes it easier to read the values. Another type of bar graph is a stacked bar graph. This type of graph displays multiple classifications in bars on top of each other, each represented by a different color or pattern. Grouped bar graphs, on the other hand, display multiple categories via bars side by side, making it easy to compare values between the classifications.