A bar graph, also called a column chart, bar chart or multiple column chart, is a chart in which data is visually represented by vertical or horizontal bars. It is used to show comparisons between values, with a bar representing each separate value. Categories or groups are commonly plotted on the horizontal axis (axis X) and a quantitative or numerical scale is plotted on the vertical axis (axis Y). Bar graphs are used to plot both continuous and discontinuous, or discrete, data.

### Easy Representation of Data

A bar graph represents data, or a set of data, in a diagrammatical manner. Bar graphs are useful in representing data with distinct units, such as years and months. They are also valuable in showing the differences, or making comparisons, between different variables. Bar graphs are valuable when countable variables, facts and data are to be demonstrated. Bar graphs show these, and other comparative values, in a distinct and comprehensive manner, giving a clearer, more understandable picture of data distribution.

### Represents Frequency

According to Deborah Rumsey in "Statistics Workbook for Dummies," bar graphs are the most poplar data display method, breaking down data into graphs and showing the relative frequency or frequency for each separate group (which is typically represented by the height of a bar).

### Easy to Prepare

Bar charts are easy to prepare, provided appropriate plotting data has been gathered and prepared. A complete bar graph requires a title, labels and a scale. According to Ronald Staszkow and Robert Bradshaw in the book "The Mathematical Palette," it takes three steps to make a bar graph: determining the categories or values that are to be placed along the horizontal and vertical axes; making the scale that is to be used to determine the numerical data; and setting the type, style and length of each bar.

### Versatile and Widely Used

There are many types of bar graphs, which can be used for various purposes. The three most common types of bar graphs include simple bar graphs, broken-bar graphs and multiple-bar graphs. A simple bar graph represents a single quantity through the height or length of the bar; a broken-bar graph is typically used to represent large values or amounts; and a multiple-bar graph is used to represent values of different items. Bar graphs are used in various industrial, educational, retail and business settings to show comparisons between values, such as the number of students with a passing grade, or the number of sales made over a particular time period.