Effects: - Hides a location. The Fidelius Charm works by hiding a secret inside of a living person, the secret being the location of a certain home in our case. Only the living person who holds the secret, called the Secret Keeper, can reveal to others where the home is located, and only by choice. The location cannot be tortured out of them or stolen from their mind - it must be given voluntarily, either verbally or through writing on a page. Anyone told the secret then becomes a secondary Secret Keeper. They cannot reveal the secret though - only the primary Secret Keeper can do that. Should the primary Secret Keeper die, all secondary Secret Keepers become primary Secret Keepers. Should the Secret Keeper die without telling anyone the secret, then it will die with them. The spell will still be in effect, but no one will know the location of the home. Any human being can be a Secret Keeper. 

A location under the Fidelius Charm will remain hidden even from people who may have known about it before the charm was cast. Take 12 Grimmauld Place for example. It was known by the Death Eaters that Harry Potter inherited this home from his godfather when he died. They sat and watched the location, but were unable to see it because it was under the protection of the Fidelius Charm. You also cannot hear what is happening inside of a location protected by the Fidelius Charm, nor can you feel the location or plot it on a map. - Charms Lesson 6, Fifth Year, Hogwarts School of Witchcraft and Wizardry.

Spell Type: - Defensive.

Spell Block: - 

Unknown To Me. If anyone already knows it or gets to know it, please get in touch with me and help me by letting me know it.