The British Standard for electric mains outlets and plugs.
"UK plugs are no doubt among the safest in the world, but also among the most hulking and cumbersome. That’s why people often make fun of them saying that a British plug is mostly bigger than the appliance it is connected to… Moreover, the bottom-heavy design of the plug makes it a perfect caltrop."
—WorldStandards
You've probably seen them , and even if you haven't, you've probably heard the joke that British plugs are as large as the appliance they connect, and even as an emigré Brit, I have to agree. They are fucking huge, and have three pointy ends that, if trodden on, cause more pain than any LEGO™ brick. But it turns out there's a reason they are the way they are, and that, people is SAFETY.
"Not sure which country yours is, but if it's the one I'm currently living in, your plugs are a bloody disgrace, what with their EZ-Bend™ prongs and FallingOutAtTheDropOfAHatness.
That said, we've all experienced your pain. It's part of why we have the NHS."
—comment on Reddit
Plug sockets are earthed, each plug has three prongs, live, neutral and ground. The ground prong is longer, and designed to engage the socket first; this action slides a cover off the socket's live and neutral holes, meaning it's harder to stick a knitting needle in and electrocute oneself (ask me how I know). in addition, most sockets have a switch for easy disonnection of the mains power. The plug itself has a removable fuse of 3, 5 or 13 amps to protect the circuit and the applicance, and consequently, the user. This goes a long way to explain the dimensions of the plug.
BQ24
$ xclip -o | wc -w
288