Why your plug looks like that.

Early electric homes were wired for one thing: light. The wiring ran to the lamp sockets overhead, so the first electric irons and toasters didn't plug into a wall at all — they screwed into a light socket, borrowing the bulb's circuit. To use the iron you unscrewed the bulb.

In 1904 Harvey Hubbell patented his separable attachment plug so a device could be unplugged without unscrewing anything — the appliance and the supply finally came apart at a connector instead of a thread. The flat-blade pattern that descends from his work is why North American Type A looks the way it does: two flat pins, no ceremony.

The British Type G (BS 1363) was standardised in 1947, during postwar rebuilding, and it is the heaviest domestic plug in the world for one reason: copper was scarce. To wire more sockets with less wire, Britain adopted ring final circuits — a loop of cable feeding many sockets rather than a separate run to each. But a ring can carry far more current than any one appliance's flex is rated for, so the circuit itself couldn't protect the appliance. The fuse had to move somewhere closer.

So it moved into every plug — typically 3 A for electronics, 13 A for heaters — which is the bulge you feel in a British plug and the reason it's the only common plug that carries its own fuse. Add shuttered sockets that only open for the longer earth blade, decades ahead of their time, and you get the safest and most painful-to-step-on plug ever made. It's over-engineered because 1947 Britain couldn't afford not to be clever.

Across the Channel, the continent settled on a different idea of earthing. The side-contact grounding design behind Type F — the earth carried by spring clips on the plug's sides rather than a third pin — dates to 1920s Germany, its invention commonly attributed to Albert Büttner. Its everyday name, Schuko, abbreviates Schutzkontakt: protective contact.

Schuko spread across continental Europe, which is why so much of the continent shares a single socket while the world does not — though even here there's a family quarrel. France earthed the other way round, with a pin sticking out of the Type E socket into a hole in the plug, and modern plugs are usually hybrids built to satisfy both.

Electrification happened country by country. Each one chose its voltage, its frequency and its connector before international travel with appliances was even imaginable — there was no traveller to design for, and no committee that could have bound a world that wasn't yet wired. By the time anyone wanted their kettle to work abroad, every nation had already poured its choice in concrete.

The roughly fifteen plug types this site catalogs are those fossilised national decisions, frozen from the age before anyone thought they'd need to match. You can't un-choose them now — you can only look them up. That's what the trip card is for: pick where you're going and every plug you own gets its verdict, straight from the geometry.