The Difference Between a Computer Virus, Worm and Trojan Horse

• Virus: A program or piece of code that is loaded onto your computer without your knowledge and runs against your wishes.
• Trojan horse: A destructive program that masquerades as a benign application. Unlike viruses, Trojan horses do not replicate themselves
• Worm: A program or algorithm that replicates itself over a computer network and usually performs malicious actions
• Blended threat: Blended threats combine the characteristics of viruses, worms, Trojan Horses, and malicious code with server and Internet vulnerabilities .
• Antivirus program: A utility that searches a hard disk for viruses and removes any that are found.   
  
  Tips to Combat Viruses, Worms and Trojan Horses on Your Computer
  
  
  Keep The Operating System Updated
  
  
  The first step in protecting your computer from any malicious there is to ensure that your operating systems (OS) is up-to-date. This is essential if you are running a Microsoft Windows OS. Secondly, you need to have antivirus software installed on your system and ensure you download updates frequently to ensure your software has the latest fixes for new viruses, worms, and Trojan horses. Additionally, you want to make sure your anti-virus program has the capability to scan e-mail and files as they are downloaded from the Internet, and you also need to run full disk scans periodically. This will help prevent malicious programs from even reaching your computer.