Why does a pen cap have a hole? Is that tiny jeans pocket a mistake? Vote, then see the real reason.
A leftover, an accident or a compromise. It was not made for you, and sometimes it only stays because it always has.
Put there on purpose to solve a problem you may never have noticed: safety, strength, cost, or a quirk of use.
Five new cards every day, the same five for everyone. Share your score as text, keep a streak, or browse all 38 cards at your own pace.
Every card links to the standard, museum, manufacturer or publication behind its answer. Where the popular explanation is a myth, we say so.
Cat’s eyes in the road
The little bumps on the F and J keys
Manhole covers are round
The bumpy yellow tiles at crossings