Troia

Troy — Greek Troia, Latin Troia, Homeric Ilios — was the city besieged by the Greeks for ten years in the Iliad, the city whose fall Homer's epics describe. In the story, the Greeks had been unable to breach Troy's walls by direct assault for a decade. On the counsel of Odysseus, they built a large wooden horse, concealed warriors inside it, and presented it to the Trojans as a votive offering to Athena before pretending to sail away. The Trojans brought the horse inside their walls. That night, the Greek warriors crept out and opened the gates for the returning fleet. Troy burned. The Trojan War was over.

Whether Troy is a historical city is a question archaeologists have debated for two centuries. Heinrich Schliemann's excavations at Hisarlik in northwestern Turkey beginning in 1870 revealed a site of overlapping Bronze Age cities, the most famous of which — Troy VIIa — dates to roughly 1180–1200 BCE and shows evidence of violent destruction consistent with an attack. Most modern archaeologists believe Hisarlik is almost certainly the Troy of legend, or at least the settlement that inspired it. The wooden horse, however, leaves no archaeological trace. Ancient commentators — Thucydides, Strabo — were already skeptical about its literal truth.

The word 'Trojan' entered English as an adjective describing people and things from Troy. 'Trojan horse' as a metaphor for a concealed threat introduced under false pretenses appears in English by the 17th century and was used in political discourse before computers existed. When computer scientists began classifying malicious software in the 1970s and 1980s, the taxonomy required names: virus (self-replicating code), worm (self-propagating through networks), and trojan horse (malicious software disguised as legitimate software). The first published use of 'Trojan horse' in a computing context is attributed to Daniel Edwards of the NSA in a 1974 paper on computer security.

The abbreviation 'trojan' — lowercase, standalone — became standard in cybersecurity parlance by the 1980s and 1990s. Unlike viruses, trojans do not self-replicate; unlike worms, they do not spread autonomously. They work only through deception — the user must be tricked into installing them. The metaphor is exact: a trojan in computing is always a gift that should not be accepted. The city that Homer's epics destroyed by this method is now in every antivirus software's threat taxonomy, in every IT security briefing, and on every malware scan report. The wooden horse outlasted the city by three thousand years.