he Trojan Horse is a tale from the Trojan War about the subterfuge that the Greeks used to enter the city of Troy and win the war. In the canonical version, after a fruitless 10-year siege, the Greeks constructed a huge wooden horse, and hid a select force of men inside. The Greeks pretended to sail away, and the Trojans pulled the horse into their city as a victory trophy.
The Trojan horse, a huge hollow wooden horse constructed by the Greeks to gain entrance into Troy during the Trojan War, was built by Epeius, a master carpenter and pugilist. The Greeks, pretending to desert the war, sailed to the nearby island of Tenedos, leaving behind Sinon, who persuaded the Trojans that the horse was an offering to Athena (goddess of war) that would make Troy impregnable.
Despite the warnings of Laocoon and Cassandra, the horse was taken inside the city gates. That night Greek warriors emerged from it and opened the gates to let in the returned Greek army.
The story is told at length in Book II of the Aeneid and is touched upon in the Odyssey. The term Trojan horse has come to refer to subversion introduced from the outside. Beginning in the late 20th century, the name "Trojan horse" was applied to deceptively benign computer codes that seem like legitimate applications but are written to damage or disrupt a computer's programming or to steal personal information.