What is a Trojan horse as used in computer?

A Trojan horse is a type of malware that disguises itself as a legitimate file or software in order to trick users into downloading and installing it on their computer. Once installed, a Trojan horse can perform a variety of malicious actions, such as stealing sensitive information, deleting files, or allowing unauthorized access to the infected computer. Trojans are often used by cybercriminals to gain access to a victim's computer and carry out malicious activities without their knowledge.