The United Kingdom is sort of like Diet United States. Same flavour, not nearly as fattening.
Back in olden times (read:1707), England (which included Wales at the time) and Scotland threw caution to the wind and came together in holy matrimony, a beautiful union that brought about crying, heavy drinking and The United Kingdom. See, way back before then, England and Scotland had their own monarchies, meaning both were known as The Kingdom of England and The Kingdom of Scotland. However, in 1603, James the 6th of Scotland became James the 1st of England, meaning the two countries had joint Royalty. Sort of like joint custody, but if the child was a giant and had mass power over its parents.
Pictured: King James I of England
Over the past 300 years, the United Kingdom's been involved in many of the major shitastrophes that have occured around the world (mainly Europe), including The American Revolution (spawning the Hollywood cliche that all bad guys have posh English accents), The Napoleonic Wars (strange that everyone forgets that France nearly brought Europe to it's knees and continue to call the French cowards) and both World Wars (eagerly awaiting the sequel).
Welcome to class! Sit down, spit out that gum and pay attention!