What is a Virus or Trojan Horse?

A computer virus is a computer program that can copy itself and infect a computer without permission or knowledge of the user. A virus can only spread from one computer to another when its host is taken to the uninfected computer, for instance by a user sending it over a network or carrying it on a removable medium such as a floppy disk, CD, USB drive or by the Internet. Additionally, viruses can spread to other computers by infecting files on a network file system or a file system that is accessed by another computer. Viruses are sometimes confused with computer worms and Trojan horses. A worm, however, can spread itself to other computers without needing to be transferred as part of a host. A Trojan horse is a file that appears harmless until executed. In contrast to viruses, Trojan horses do not insert their code into other computer files. Many personal computers are now connected to the Internet and to local-area networks, facilitating their spread. Today’s viruses may also take advantage of network services such as the World Wide Web, e-mail, and file sharing systems to spread, blurring the line between viruses and worms. Furthermore, some sources use an alternative terminology in which a virus is any form of self-replicating malware.

Some viruses are programmed to damage the computer by damaging programs, deleting files, or reformatting the hard disk. Others are not designed to do any damage, but simply replicate themselves and perhaps make their presence known by presenting text, video, or audio messages. Even these benign viruses can create problems for the computer user. They typically take up computer memory used by legitimate programs. As a result, they often cause erratic behavior and can result in system crashes. In addition, many viruses are bug-ridden, and these bugs may lead to system crashes and data loss.

A Trojan horse is a program that installs malicious software while under the guise of doing something else. Though not limited in their payload, Trojan horses are more notorious for installing backdoor programs which allow unauthorized remote access to the victim’s machine by unwanted parties – normally with malicious intentions. Unlike a computer virus, a Trojan horse does not propagate by inserting its code into other computer files. The term is derived from the classical myth of the Trojan Horse. Like the mythical Trojan Horse, the malicious code is hidden in a computer program or other computer file which may appear to be useful, interesting, or at the very least harmless to an unsuspecting user. When this computer program or file is executed by the unsuspecting user, the malicious code is also executed resulting in the installation of the malicious Trojan horse program.


We have many tools at our disposal for removing Virus and Trojan Horse infected files. Each virus and trojan is different, and many require varying degrees of expertise. Many computers we’ve dealt with have multiple virus and trojan horse infections, and many users are not aware they have a problem until something stops working.

Several customers complain that they still become infected even though they are running a firewall application. That’s a popular misconception; that a firewall will stop you from becoming infected with a virus or trojan. The firewall will sometimes stop your computer from sending out infections to other computers, but most Trojan Horses arrive and look like legit applications. Because of this, many users actually run the Trojan Horse code without even knowing it.

Protection From Future Infections

We can recommend many Anti-Virus applications and Firewalls for your particular needs. We’ll even teach you how to run these programs with as little effort as possible. Several of our solutions are a “set it and forget it” type of program.