Weasleys' Wizard Wheezes began as an owl-order business conceived and run by Fred Weasley and George Weasley during their time as students at Hogwarts School of Witchcraft and Wizardry. Their ambition was to open a physical shop, a dream made possible by a one-thousand Galleon investment from Harry Potter, who gave them his Triwizard Tournament winnings in 1995. The twins were notorious for developing and testing their products, such as Skiving Snackboxes, on themselves and other Hogwarts students. After a dramatic and defiant departure from the school under the tyranny of Dolores Umbridge in 1996, they secured their premises at Number 93, Diagon Alley. The shop officially opened in the summer of 1996 and was an immediate and overwhelming success. The exterior was described as so bright and vibrant that it made the other shops look drab. Inside, the store was crammed floor to ceiling with merchandise, creating a bustling and joyous atmosphere. Products ranged from classic joke items like Extendable Ears to more complex creations like Daydream Charms and the “WonderWitch” line of products, which included Love Potions. Following the death of Fred Weasley during the Battle of Hogwarts, George Weasley continued to run the successful business.
The business serves as a major subplot throughout the middle books, showcasing the ingenuity, ambition, and humor of the Weasley twins. In Harry Potter and the Goblet of Fire, the twins begin selling their products, leading to Harry Potter providing the startup capital. In Harry Potter and the Order of the Phoenix, their mail-order service thrives in defiance of Dolores Umbridge's oppressive rules, culminating in their spectacular flight from Hogwarts after creating a Portable Swamp. In Harry Potter and the Half-Blood Prince, Harry Potter, Ron Weasley, and Hermione Granger visit the successful physical shop. The store stands as a symbol of defiance and joy. Items from the shop play a role in the plot; for instance, Draco Malfoy uses Peruvian Instant Darkness Powder purchased from the store to facilitate the Death Eaters' entry into Hogwarts. In Harry Potter and the Deathly Hallows, the shop continues to operate through owl order, and their products, such as Decoy Detonators, prove useful.