The Button was a magical button, originally belonging to a set, which enables the magician who touches it to travel to The Neitherlands.
The buttons were infused with magic to allow transport to the Neitherlands, and from there the user can pursue their next location. Transport with the Buttons did not require it's user to be a Traveller, nor execute any spell, physical contact with the buttons caused the user to instantly appear in the Neitherlands which is why the buttons are placed within small hexagonal cases.
Helen and Jane Chatwin were given a set of Buttons by the magical Talking Rabbits of the Wandering Desert in Fillory. Their purpose was to enable the Chatwin family to travel from Earth to Fillory as they wish, instead of waiting for Ember to allow them. Helen considered them a perversion of magic so she hid them.
Years later, Jane found one of the buttons and used them to manipulate Penny into traveling to Fillory, which at the time was under the authority of Martin Chatwin, with the help of the Physical Kids, so they could battle him.
After it was discovered that a young Martin Chatwin was being kept from entering Fillory by the land's gods, Jane Chatwin promised her brother that she would find a way for him to travel there again. The next time she went to Fillory, she caught one of the Questing Creatures, the White Lady, who was forced to grant her one wish. Jane's wish was for a gift that would allow her to travel to Fillory whenever she wanted and so she was given a magical button to do just that. When returning to Earth, she gave it to Martin, who was forced to trust it with one of their younger siblings, who agreed to hide it from Plover.
Later on, Quentin realized that Penny had inadvertently Projected himself to Fillory, and he and the Physical Kids went to Christopher Plover's Estate, which had been transformed into a museum, to research Plover, who they then assumed was the true identity of The Beast. They learned that the younger Chatwin children were constantly abused by the Plovers, as well as learning that The Button was, in fact, real, and it was hidden somewhere in the house.
After they'd eventually acquired it, the Button served its purpose multiples times after their final battle with The Beast, but was lost when Quentin, while pursuing the help of an Underworld Gatekepper with Julia, was forced to trade it for passage to the Land of the Dead.
- In the books, Penny is able to travel to The Neitherlands without the help of the button, due to his discipline being Interdimensional Travel, but he was not able to take people with him, which was what forced him to use the Button.
- In the first season of the show, Penny, even though being a Traveller, was not able to travel to The Neitherlands without the Button because he had not yet mastered his abilities. However after training with Mayakovsky, he traveled from there without the aid of the Button as seen in Ramifications.