There has probably been a few threads along these lines over the years but screw it I'm starting another one. Rowling is rather famous for worldbuilding in broad strokes, and fanfiction and speculation has happily filled in the gaps. What ideas have you added to your own mental version of the wizarding world and how it works? Some of mine. The landmass of UK is around 15% more than muggles realize, much of if this is taken up by large hidden pureblood estates and ancient forested reserves. An important sanctuary for the isles magical creatures and plants. Avalon is an entire hidden island which is an important selkie breeding ground off the coast of Wales. It is off limits to all humans, magical or not. Hags have colonised several supposedly lost tube stations. A Muggle train stopping accidentally is going to have a bad time. Hermione names one of her kids Matilda. There are too many parallels and it's to perfect for her not to. You can't transfigure things into noble metals which is why gold/silver/copper is the basis of the currency. Wizard gold is enchanted however and cannot be seen by muggles. The traditional train ride started as a Muggleborn transport as they had no magical means of arriving, but the Hogwarts Express was so novel and cool to the wizard raised kids they demanded to be allowed to go on it too until administrators realised this was far more convenient than people appearing in willynilly. Also if you take yourself across across the street from Kings Cross to St Pancreas station you can find the International Travel Office situated in the clocktower. Centaurs have largely cornered the potion ingredient market as many of the plants grow on their reserves. Magic mushrooms are a potent magical plant that slipped ministry control in the 14th century and became so widespread and well known they could not be recalled. House elves are basically the puritans of the elf world. Elves without human imposed structure tend to become lazy immoral alcoholic hedonists. Alternatively house eves are the magically twisted results of centuries of pureblood inbreeding. For every 'pure' child there are many silent siblings that are not acknowledged as such in polite society. Dobby is Malfoy's secret brother. - One day I am going to do something with this plot bunny I sware. What have you guys come up with over the years?