Trojan
A Trojan (or Trojan horse) is a type of malicious software that pretends to be safe or useful, but actually hides harmful functions inside. Unlike viruses, Trojans do not spread by themselves — they rely on tricking the user.
How it works
A Trojan is usually disguised as a normal program, file, or update. When the user installs or opens it, the Trojan activates and starts performing hidden actions without permission.
What a Trojan can do
Depending on its type, a Trojan may:
- steal personal data and passwords
- give attackers remote access to the system
- download other malware
- spy on user activity
Because it looks legitimate, it can stay unnoticed for a long time.
How Trojans spread
Common ways Trojans spread include:
- fake software downloads
- email attachments pretending to be documents
- cracked or pirated programs
- fake updates or pop-ups
The key element is deception.
How to stay protected
To avoid Trojans:
- download software only from trusted sources
- never install unknown “updates”
- use antivirus and keep it active
- be cautious with email attachments
Awareness is one of the strongest defenses.
Simple example
A Trojan is like a gift box that looks valuable on the outside, but once opened, something harmful comes out instead.
Related terms
- What is Backdoor?
- What is Spyware?
- What is Virus?
Source
Information simplified from the Wikipedia article “Trojan horse (computing)”.