Bar graphs, or bar charts, are a way of representing data visually; printable bar charts enable people giving presentations to convey digital information on paper. They are similar to line charts but are often used to show discrete components instead of how something changes over time.
Bar charts are fairly simple and can be made using only straight lines. As a result, early printers, many of which couldn't print thin lines at angles, could print simple bar charts, making them popular options in the early days of business computers. Their simplicity still makes them a popular option for conveying certain types of information.
One of the primary advantages of bar charts is that they allow people to compare information visually. Bar charts are useful for comparing categories. An example bar chart might show the average temperatures in various regions. While numerical data can show how hot or cold certain areas are compared to others, a bar chart can better show relative temperatures.
Most office software contains tools for bar charts. Newer software is not bound by the look of older bar charts. Tools can create a pseudo-3D look or even stack multiple bar charts on top of each other. These tools enable people share information in a visually compelling manner instead of having to rely on bland visual representations.