Why do histogram bars touch when bar chart bars do not?
You can lose marks fast here because the two graphs look almost like twins. The difference is not decoration , it comes from the kind of data you are showing. If your data are labels like sport, fruit, or eye colour, you want a bar chart. If your data are numbers measured on a scale like mass, height, time, or temperature, you usually want a histogram.
A histogram is built for numerical data grouped into intervals, and the bars join because the values run continuously from one interval to the next. A bar chart uses separate categories, so spaces stay between bars. In a histogram, what matters is the area of each bar, not just the height.
A histogram is a graph for numerical data split into class intervals, where the bars touch and each bar’s area shows the frequency or relative frequency.
A bar chart works differently. The bars are the same width, they are separated, and the height alone gives the frequency.
A bar chart shows how often different categories occur using equal-width bars with gaps between them, and the bar height gives the frequency.
The sneaky part is that some wrong graphs look close enough to fool you in a test. If the horizontal axis shows categories, it is not a histogram. If the data are continuous and the bars have gaps, that is also wrong.
If you are unsure, ask yourself: are you sorting named groups, or are you grouping numbers into ranges? Named groups mean bar chart. Number ranges mean histogram.
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