A donut chart is a representation of different categories like a Pie chart, the difference is just that there is no center in the donut chart. It is a hollow visualization, having dimensions on the circumference. It helps the person to see directly at the proportion.
Why do you need it?
We need that chart to see categories in a better way than a pie chart could. Categories on the donut chart don’t confuse the mind to look at the center and gives the direct visualization of the proportions.
What kind of data you can visualize with it?
If you have numeric-data with a variety of categories, then this chart is beneficial. Assume you have data of items in a fashion-mart like accessories, shoes, clothing, handbags, and wallets, etc., then we can use this chart to see the stock of which item is in bulk and which one is about to end.