The Perils of Pie Charts

"The only worse design than a pie chart is several of them." - Edward Tufte, B-The Visual Display of Quantitative Information

Pie charts are a perennial favourite of tech-y dashboards and news stories everywhere. Got a couple values that (hopefully) add up to 100%? shove 'em in a pie. But they have their issues.

Beware of pie charts and charts where viewers are asked to compare quantities located in 'spatial disarray' both within the chart and across multiple charts (specifically pies). Pie charts have a low data-density and fail to order numbers in an easily readable visual sequence.