Magic charms, usually just called charms, are magical objects in The Sims: Makin' Magic.
They can be used by any magical family member of the proper age. Adult charms are made in the EverAfter Crafter, while children make charms in the MagiCo NeoMagical Newt. Both of these objects can be purchased in Buy mode.
The number of times an adult charm can be used depends on the type of charm and the Mechanical skill of the maker. Kids' charms always get six charges. Charms glow and spin, but become dimmer as more of their charges are used up. A charm that appears to be dark may still have a few charges left, so check before getting rid of it.
To use a charm, click on it, then click on "Cast...", then click on the name of the charm. The Magic Mood charm has options to "Mood Me Up" or "Mood Everyone Up", and the charm will not be cast unless one of those options is chosen. If a charm cannot be clicked, then all its charges have been used. Since charms can't be recharged, there's no reason to keep it around.