Diagon Alley, the wizarding high street located in London, is only accessible to wizards, hidden from Muggles. The only Muggles given access are those accompanying their Muggle-born children.
However, Muggles are allowed access to it if they need to accompany their Muggle-born magical children. If a wizard or witch needs something, chances are that it can be found in Diagon Alley. One entrance to Diagon Alley can be reached on foot by passing through the Leaky Cauldron (a wizarding pub/inn).
Why are Hermione's parents allowed to Diagon Alley?
They were able to get in because of Hermione. They were Hermione's guardians and they were required to be there when she shopped for the materials in Diagon Alley. Muggle born students parents can accompany them when they go for back to school shopping.
Wizards can make locations Unplottable on a map (and that's without even counting the Fidelius Charm). They have muggle-repelling spells that make muggles see magical things as mundane and uninteresting (Hogwarts), not see them at all (the Knight Bus), or get distracted away from them (the Quidditch World Cup).
For the Muggle-borns who are chosen to study at Hogwarts, Professors from Hogwarts pay them a visit at their homes and explain the situation to them and their parents. In Harry's case, Hagrid was chosen to be the escort.
How Are Muggleborns Told That They're Magical? - Harry Potter Explained
Do Hermione's parents know she's a witch?
She and her husband were proud and accepting of their daughter's identity as a witch, which explained some strange things which happened around her when she was a child. They entered the magical world in 1992 to buy Hermione's school supplies, and were assisted by Arthur Weasley.
The pure-blood wizards and witches featured in the Harry Potter books are almost all supremacists, while there are some of them who do not advocate ancestral superiority; the Potters, Weasleys, and Longbottoms are old pure-blood families, but no known members of these families are sympathetic to supremacist aims.
If, by unfortunate means, Muggles do happen to observe the working of magic, the Ministry of Magic sends Obliviators to cast Memory Charms upon them, causing them to forget the event. Some Muggles are aware of the wizarding world.
Those who could not prove that they had magical heritage — in other words, any Muggle-born and potentially some half-bloods — were sentenced to Azkaban for having "stolen" magic. Some, however, were apparently released after being stripped of their wands and their jobs, and ended up homeless.
Why is Harry a half blood if both his parents are wizards?
By the 1990s, most of the magical population were half-bloods. The children of Harry and Ginny Potter were considered half-bloods because although Ginny was pure-blood, Harry's mother was Muggle-born. The term was used as an insult from members of fanatical pure-blood families.
Her real parents were Daneel and Dean Novak, Pureblooded wizards. Turns out Daneel was Tom Riddles younger sister, Daneel Riddle. Of course, the Riddles were related to Salzar Slytherin himself, and this made Hermione the living heir of Slytherin.
Hermione's Parents Had Their Memories Restored According To Harry Potter Canon. This tragic ending for Hermione and her parents never happened in the Harry Potter books. This is because Hermione didn't just erase her parents' memories—she rewrote them using a False Memory charm.
Students might wear their muggle clothing underneath when they are getting off of the train, for changing convenience, or maybe when it's a bit colder. But on normal school days, it is likely that students only wear Hogwarts robes.
What does Harry Potter say instead of Diagon Alley?
After Harry mistakenly says "diagonally" when using Floo Powder to travel to Diagon Alley, he ends up in Bourgin & Burkes, a dark arts store in Knockturn Alley. There, he sees all manner of dark objects including an opal necklace, which we can just about make out.
It is true that muggles can't see dementors, though they can feel the effects. However a Patronus is a magical guardian formed out of powerful positive emotion, so there is no real reason that muggles won't be able to see them.
If the muggle knew about the magic world then he would be sentenced by wizard. If he did not know and just, lets say robbed a wizard and shot him with no knowledge of it. Then the cops would report who it was and what he had, Ministry of Magic would hear about it through their connections in the muggle world.
Even Muggles feel their presence, though they can't see them. Get too near a Dementor and every good feeling, every happy memory will be sucked out of you. If it can, the Dementor will feed on you long enough to reduce you to something like itself...
Muggle-borns inherit magic from a distant ancestor; they are descended from Squibs who have married Muggles and whose families had lost the knowledge of their wizarding legacy. The magic resurfaces unexpectedly many generations later.
History. This fake wand was commissioned by Albus Dumbledore so that Jacob Kowalski could blend in with and more easily hide in plain sight of witches and wizards during the global wizarding war, as he was a No-Maj.
Keep in mind that Filch was a Squib- so did have some magical blood despite not being able to use magic- so there's always a super slim hope that they have 'latent' ability or even some minor ability to be developed. A Muggle has none (or at least none they know of...) and can never learn real magic.
Also Muggles believed that dragons were a mere myth, but had been known on occasion to glimpse these beasts. To prevent dragons from being seen by Muggles, the beasts were kept on dragon reserves around the world, most of which were far from human habitation.
Family. Snape's family background is mostly shown in flashbacks during the course of the last three novels. Snape was born to Eileen Prince, a witch, and Tobias Snape, a Muggle, making him a half-blood (hence the name, "Half-Blood Prince").
The Malfoy family comes from a long line of rich witches and wizards within Harry Potter, and Lucius Malfoy has copious amounts of money at his disposal. He resides in a gigantic mansion with his family, named Malfoy Manor, and owns some of Harry Potter's most powerful objects, including a golden Time-Turner.
The Malfoys were a pure-blood wizarding family who were one of the Sacred Twenty-Eight - a list of pure-blood wizarding families published in the 1930s. Known for being aligned with the Dark Arts, the Malfoys had a history with Voldemort, with Lucius Malfoy being a Death Eater in You-Know-Who's innermost circle.
