Bar charts are one of the most effective ways to compare quantities across different categories. You typically use a bar chart when you want to highlight differences between groups, such as sales by product, population by country, or survey results by age range. Unlike line charts, which are ideal for illustrating trends over time or continuous data, bar charts focus on comparing discrete categories side by side. The bars make it easy to see which category is larger or smaller, and how different groups relate to each other in terms of value.

A key configuration difference between bar charts and line charts in Chart.js is how the data is represented and interpreted. In a bar chart, each bar corresponds to a category on the x-axis and its height represents the value on the y-axis. Line charts, on the other hand, connect data points with lines to show how values change over a sequence, often time. Bar charts can be either vertical or horizontal, but the vertical orientation is most common for comparing categories. Chart.js allows you to include multiple datasets in a single bar chart, which is useful for comparing values across the same categories, such as sales in different years.

To build a vertical bar chart with multiple datasets in Chart.js, you need to specify the type as bar, define your labels for each category, and include one or more datasets, each with its own label, data array, and color settings. The following example illustrates how to create a bar chart that compares two datasets across several categories.