What is a Computer Virus?

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A Computer Virus is a relatively small software program that is attached to another larger program for the purpose of gaining access to information or to corrupt information within a computer system. Some computer viruses may be relatively harmless. For example, some of them just cause a certain message to pop up on a user's computer screen. Other viruses can be deadly to the computers they infect, erasing information and hard drives, stealing data, and slowing down the entire computer system. Like other software programs, someone must create and write a computer virus; once they are created, viruses can multiply rapidly and spread themselves from computer to computer.

Computer Virus Definition & Characteristics:

A Computer Virus is a program that can copy itself and infect a computer without the permission or knowledge of the user. A computer virus has 2 major characteristics: the ability to replicate itself, and the ability to attach itself to another computer file. Every file or program that becomes infected can also act as a virus itself, allowing it to spread to other files and computers. The term "computer virus" is often used incorrectly as a catch-all phrase to include all types of Malware such as Computer Worms, Trojan Horses, Spyware, Adware, and Rootkits - all of which are slightly different than Computer Viruses.

A computer virus needs another program in order to be able to be activated and infect other computers files. Essentially, a computer virus rides piggyback on another file into your computer - once it is executed, the virus will continue to replicate and attach itself to other program files and continue to spread.

A Brief History of Computer Viruses:

Although computer scientists were aware of the theoretical possibility of computer viruses for decades, it was not until the 1980s that viruses began to gain a hold and multiply in large numbers. With the advent of the personal computer, floppy disk drives, and other portable information storage devices, it became easier to program and transfer viruses from one machine to another. Fred Cohen is often cited as the first person to use the term "computer virus" in an academic paper in 1984, although some suggest that he may have learned it from his mentor Leonard Adleman (more info: History of Computer Viruses).

Does My Computer Have a Virus?

Of course, if you ask anyone the question “what is a Computer Virus?”, the reply is likely going to be a bit jumbled. There are many different forms of computer viruses, although many have the same goal; to slow the infected computer system, steal and/or copy information from the computer, and attach itself to sent files and attachments in order to spread to other computer systems. The following are a few telltale signs that your computer might have a virus:
• Slow response and slow program execution
• Random hard drive crashes and restarts
• Distorted graphics and text
• Files that have mysteriously vanished
• Extensive pop-up ads
• Inability to open files with existing passwords
How Can I Protect My Computer from a Virus?

It is far better to avoid computer viruses and take proactive measures to protect your computer system than it is to clean up after them once they have gotten into your computer and caused damage. The following tips will help increase your odds of avoiding infection from a computer virus:
• Download programs only from trusted, reputable websites
• Install a quality Internet firewall
• Do Not open suspicious emails or email attachments
• MOST IMPORTANTLY — Make sure you have a trusted anti-virus program installed on your computer - such as Norton Antivirus, NOD32 Antivirus, or Kaspersky Antivirus.
Article last updated March 4, 2012.

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