Histograms
Bar Charts are a good visualiation option for displaying Categorical data. As in the case of the Staple foods example, when you have data like car sales, scores of individuals, or GDP numbers of different countries, bar chart is a good option.
What if you have numerical data instead? That's where Histograms come into play.
Let's use the Statistics test scores example to drive the point here.
Take a look at the charts below.
As you can see both look similar. However, there are many differences between the two.
For starters, the bar chart is used for categorical data, whereas the Histogram is used to represent numerical data. In the above example, scores of individual students are shown in a bar chart as this is categorical data. For the same reason, a bar chart has gaps between each bar.
Numerical data on the other hand is continuous - you don't have any gaps between numbers! Hence a histogram has no gaps among the bars. In the above example, a histogram is used to show the number of scores over different ranges of scores - 10 students scored less than 30 for example.
Note: You may want to refresh yourself on the Data Measurement section in case the data types - numerical vs categorical doesn't make sense.