Wand-Lighting Charm

Lumos is a charm that causes the tip of the caster's wand to light up. Evidently the light has some heat to it, because Alastor Moody used the light to burn paper. Its counter-spell is Nox. It is taught in first year charms classes. Lumos is found in the Standard Book of Spells, Grade 2.

Known practitioners

 * Albus Dumbledore
 * Arthur Weasley
 * Barty Crouch Jr.
 * Cedric Diggory
 * Harry Potter
 * Hermione Granger
 * Katie Bell
 * Lavender Brown
 * Luna Lovegood
 * Minerva McGonagall
 * Nymphadora Tonks
 * Quirinus Quirrell
 * Ron Weasley
 * Severus Snape

Etymology
The incantation Lumos is derived from the Latin lumen meaning "light."

Behind the scenes

 * It is possible this charm is not affected by The Trace, perhaps because it is incredibly simple and looks like a flashlight, so this spell could be used outside Hogwarts.
 * In the opening of The Wizarding World of Harry Potter, Daniel Radcliffe, Michael Gambon, Bonnie Wright, Rupert Grint and James and Oliver Phelps tried to use Lumos to illuminate Hogwarts Castle. However, they did not succeed and they tried a stronger version of this spell, Lumos Maxima.
 * Other versions of the spell were used in the movies and games:
 * Lumos Solem was used by Hermione Granger in Harry Potter and the Philosopher's Stone, creating a beam of light with the intensity of the sun.
 * Lumos Maxima was performed by Harry Potter at the Dursleys' house in Harry Potter and the Prisoner of Azkaban, and was also used in the Horcrux cave in Harry Potter and the Half-Blood Prince by Albus Dumbledore and Harry Potter. It creates an extremely large ball of light at the end of the wand, which can even be cast off to hover and light a greater area.
 * In the video game adaptation of Harry Potter and the Prisoner of Azkaban, Ron Weasley has a version called Lumos Duo, which creates a conection between the caster's wand and a creature or object.
 * In the PS2, XBox, Gamecube, and PC/MAC versions of the video game adaptation of Harry Potter and the Philosopher's Stone, Lumos can also be cast on gargoyles, causing them to summon platforms of light tangible enough for a person to stand on.

Appearances

 * Harry Potter and the Philosopher's Stone (film)
 * Harry Potter and the Philosopher's Stone (video game)
 * Harry Potter and the Chamber of Secrets
 * Harry Potter and the Chamber of Secrets (video game)
 * Harry Potter and the Prisoner of Azkaban
 * Harry Potter and the Prisoner of Azkaban (film)
 * Harry Potter and the Prisoner of Azkaban (video game)
 * Harry Potter and the Goblet of Fire
 * Harry Potter and the Goblet of Fire (film)
 * Harry Potter and the Order of the Phoenix
 * Harry Potter and the Order of the Phoenix (film)
 * Harry Potter and the Half-Blood Prince
 * Harry Potter and the Half-Blood Prince (film)
 * Harry Potter and the Half-Blood Prince (video game)
 * Harry Potter and the Deathly Hallows
 * Harry Potter and the Deathly Hallows: Part 1
 * The Tales of Beedle the Bard
 * Lego Harry Potter: Years 1-4
 * Harry Potter: Spells

Notes and references
Lumos Valois