Disillusionment Charm – Harry Potter Lexicon

"Disillusionment Charms should be performed daily, as their effects are apt to wear off."
-- Newt Scamander (FB)

The disillusionment charm is a charm which hides the true, magical nature of something.

History and Notes

Hippogriffs and winged horses may be kept by wizards as long as they perform a Disillusionment Charm on them regularly so that Muggles won't notice anything strange about them (FB).
One of the ways to create an Invisibility Cloak is to imbue a travelling cloak with a Disillusionment Charm (DH21).

References from the canon

Mad-Eye Moody cast a Disillusionment Charm on Harry to protect him during the trip from Privet Drive to Grimmauld Place ("I'm going to Disillusion you..."). To Harry, it felt as though someone had broken an egg on his head, like a flood of cold running down over him. When under the Charm, his body took on the appearance of whatever was behind him. He felt like a human chameleon. When Moody removed the Charm, it felt like trickling of warmth instead of cold (OP3, OP4).
The thirteen witches and wizards who came to collect Harry from number four, Privet Drive for the last time used Disillusionment Charms (DH4).
Hermione used Disillusionment Charms as part of the protective enchantments used to hide the camp she shared with Harry and Ron during the hunt for the Horcruxes (DH15).
Hermione suggested using a Disillusionment Charm when planning the visit to Godric's Hollow (DH16).
Albus Dumbledore did not need an Invisibility Cloak because he could perform a Disillusionment Charm that was powerful enough to make him effectively invisible without one (DH22).
Voldemort cast a Disillusionment Charm to conceal himself from anyone watching from Hogwarts Castle when he arrived to rob Albus Dumbledore's tomb; the Disillusionment Charm worked so well that even he could not see himself (DH24).
Vincent Crabbe, Gregory Goyle, and Draco Malfoy used a Disillusionment Charm to hide in the corridor outside the Room of Requirement during the Battle of Hogwarts, which is how they happened to sneak in when Harry, Ron, and Hermione arrived to search for the diadem of Ravenclaw (DH31).