A broken slab of granodiorite found by French soldiers in 1799 carried the same decree in three scripts. Turning that into the key to ancient Egypt took a race between two rival geniuses and a flash of insight in Paris in 1822.
Designed in 1994 to track components on Toyota-group factory floors, the QR code now pays for chai in Bengaluru and coffee in Shanghai. Its success came down to clever geometry, built-in error correction and one unusual decision about a patent.
Satellites get the headlines, but roughly 99% of intercontinental data travels through cables no thicker than a garden hose, lying on the ocean floor.
Love, 15, 30, 40, deuce. Tennis has the oddest scoring in world sport, and it is older than the modern game itself. Here is where the numbers came from, which popular theories fall apart, and how the tiebreak finally tamed the endless set.
The marathon's oddly precise distance has nothing to do with ancient Greece. It was fixed by a London race route in 1908 and made official in 1921. Here is the full story, from Pheidippides to the sub-two-hour era.
The name is barely 150 years old, and the reality was a shifting web of caravan trails and sea lanes that carried paper, religions, technologies and plague between China, India, Persia and Europe.
Started as a lighthearted joke in 1986, The Economist's Big Mac Index has become one of the most quoted guides to whether currencies are overvalued or undervalued. Here is how it works, and where it falls short.