A Trojan is a type of malicious computer program or malware that is similar to a computer virus. While Trojans are sometimes referred to as viruses, an important distinction is that viruses can execute and replicate themselves, whereas Trojans must be executed by a user. Trojans may be hidden in links or programs to infect a computer when the link or program is executed. There are several simple ways you can help protect yourself against Trojans.
Never open unsolicited emails from unknown senders. Emails from people you don't know may contain links, attachments or other traps that can get you to inadvertently install Trojans.
Avoid downloading and installing programs unless you fully trust the publisher. Some websites attempt to trick users into downloading programs that they claim will perform useful tasks, when in reality installation will only infect your computer.
Use firewall software. Firewalls are programs that can block unsolicited connections, which may help prevent Trojans. If you use Windows XP Service Pack 2 or later, Vista or Windows 7, you will have access to Windows Firewall. Make sure it is running properly by clicking "Start," "Control Panel," "Security," "Windows Firewall" and "Change Settings." Click "On" and "Apply" if it is not already on.
Use a fully updated antivirus program whenever you are using the Internet. Antivirus software can help scan links for malicious data and prevent and remove malware, like Trojans. Popular antivirus programs include Norton, McAfee, Kaspersky, AVG Free, Avira AntiVir and Avast.
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Since Trojans must be executed by users, they may be easier to avoid than other types of malware. If you never download files and never click on links outside of trusted websites, you can significantly reduce the chances of coming into contact with Trojans.