"ENQUIRY AT THE MINISTRY OF MAGIC: Arthur Weasley, Head of the Misuse of Muggle Artefacts Office, was today fined fifty Galleons for bewitching a Muggle car."
-- news article clipped from the Daily Prophet (CS12)
A division of the Department of Magical Law Enforcement in the Ministry of Magic
Arthur Weasley was the Head of the Office (until July 1996), which is meant to keep enchanted items out of the hands of Muggles. His son Ron called it "the most boring department" (CS3).
The office was a tiny and drab, but filled with files and charmed objects such as "an old toaster that was hiccoughing in a disconsolate way and a pair of empty leather gloves that were twiddling their thumbs" (OP7).
The Office also creates new laws and regulations, which can sometimes be a bit annoying for Wizarding folks (Pm).
"Artefact" is the British spelling of the noun meaning, primarily, an object shaped by human workmanship, especially one of historical or archaeological interest. "Artifact" is the American spelling.