The Worldbuilding of Harry Potter: Bridging the Gap Between Fantasy and Reality
The books and films comprising the Harry Potter franchise all take place within a fictionalized but highly realistic depiction of the modern (late 90's to early 2000's) world, with magic and other fantastical elements overlaid atop this familiar and believably real base. As a result, the stories have to do some complex worldbuilding to make wizardry fit into a predominantly ‘muggle’ (non-magical) society, while explaining why none of this magic is ever visible to us real people. Sometimes there are magical concepts that seem to exist solely to fill a particular plot hole or justify why a different magical thing is not visible to muggles, but even then, author J.K. Rowling managed to create a fantasy world that blends seamlessly with our own earth and its history. She even integrates real-world mythology and folk tales into her worldbuilding, using them as points of connection between the muggle and wizard worlds. Events such as the Salem witch trials, cryptids and mythical creatures (including the Loch Ness Monster, Phoenix, dragons, etc.), and traditional cultural stereotypes about witches and wizards all tie directly into the lore of the wizarding world. These folklore elements represent historical instances where muggles bore witness to the magical forces that wizards so thoroughly sought to keep hidden from them. Even the idea of "believing in magic" is accurate within the world of Harry Potter, as it is entirely plausible that some muggles were exposed to displays of magic that they weren't meant to see, and then told that it was 'just their imagination' by fellow muggles.
Everything about the Harry Potter universe is wondrously fantastical, yet so grounded and realistic that if it were actually a part of the real world, nothing would look any different to us. I believe this is why so many of us who read/watched the HP series as children or adolescents desperately wished it was real. The wizarding world felt accessible and familiar, like something we could take part in, and it merged so effortlessly with the muggle world that it could theoretically exist and we (as muggles) would have no way of proving it was there. By the same rule, we also have no way of proving that the wizarding world does not exist, except for the fact that it was all created by a single author.
In my opinion, Harry Potter is one of the most complete and thorough implementations of the 'low fantasy' genre (realistic world with fantasy elements added), and it represents a triumph in worldbuilding excellence on-par with the works of T.R.R. Tolkien, George Lucas and other great storytellers of the 20th century. While creating a detailed and immersive fantasy world that exists separately from the real world is a great challenge, creating one that seamlessly integrates with the real world and ties into many different myths and legends is a whole other level of lore-crafting. I don't necessarily agree with J.K. Rowling on certain social issues, but I have nothing short of respect for her literary masterpiece that is Harry Potter: the story that made magic feel more real than ever before.