Your numbers in — a pie, bar or line chart out, ready to download
A chart is a translation: it turns a column of numbers into something the eye can compare at a glance, because people read length and position far faster and far more accurately than they read digits. The three shapes here cover most of what everyday data needs. A pie answers "what is this made of", and only when the parts genuinely add up to one whole and there are few enough of them to tell apart. Bars answer "which is bigger", and they do it better than anything else, because comparing two lengths side by side against a common baseline is the one visual judgement people make almost perfectly. A line answers "what happened over time", and it earns its shape from the fact that the points are in an order that means something.
The conventions are worth knowing because breaking them misleads people even when the numbers are right. A bar chart has to start at zero — cropping the bottom of the axis exaggerates small differences into dramatic ones, and it is the single most common way an honest table becomes a dishonest picture. A line chart may start elsewhere, since it shows change rather than magnitude, but the axis should say so plainly. Pies go wrong past about six slices, when the wedges become too similar in angle to rank, and they go wrong again the moment the parts overlap or fail to sum to the whole. Colour should carry identity, never quantity, and a chart that depends on colour alone stops working for the one reader in twelve with colour-blindness — which is why the default colours here were picked to stay distinguishable under the common forms of it, and why a legend and labels are on by default.
The graphical forms are older than most people expect. William Playfair drew the first bar chart in 1786 and the first pie in 1801, inventing almost the whole vocabulary in two books about trade and national debt; Florence Nightingale used a circular relative of the pie in 1858 to show a parliamentary committee that far more soldiers in Crimea were dying of preventable disease than of wounds, and the reforms followed. Charles Minard's 1869 drawing of Napoleon's march on Moscow is still held up as the best statistical graphic ever made. What all of them share is that the picture was not decoration for the argument — it was the argument, made in a form an audience could check for itself.