Updated: 10/07/2019 by Computer Hope
Computer Virus

A computer virus is a program, script, or macro designed to cause damage, steal personal information, modify data, send e-mail, display messages, or some combination of these actions.

When the virus is executed, it spreads by copying itself into or over data files, programs, or boot sector of a computer's hard drive, or potentially anything else writable. To help spread an infection, the virus writers use detailed knowledge of security vulnerabilities, zero days, or social engineering to gain access to a host's computer.


A computer virus cannot infect a CD or DVD, as most CDs or DVDs are locked after being created, preventing additional files from being put on that disc. However, if during the creation of the disc a virus is also copied to the disc it would become infected.

Which operating systems are susceptible to viruses?

All operating systems can contract a computer virus or malware. Whether you use Android, iOS, Microsoft Windows, macOS, or a Linux variant, your computer can be at risk.

How to protect your computer from a virus

You can protect your computer from viruses by installing an antivirus protection program. Once installed on a computer an antivirus monitors, detects, and cleans any computer viruses by looking for virus signatures.

What can a virus do to a computer?

What a virus does to a computer once it has infected the computer depends on the type of virus. Most computer viruses delete data, overwrite information, display messages, and add itself to other files on the computer. Almost all computer viruses only damage the data contained on the computer and do not physically harm the computer or its hardware. For example, a non-resident virus can infect a specific file and when accessed, it can spread to other files, corrupting those files and making them unreadable.

It is possible for more sophisticated viruses, like Stuxnet, to cause physical damage to components inside the computer or the computer as a whole.

Examples of computer viruses

Below is a list of the different types of computer viruses.

Appending virus
Boot sector virus
Cavity virus
CMOS virus
Companion virus
Encrypted virus
Executable virus
MBR virus
Macro virus
Multipart virus
Non-resident virus
Overwrite virus
Polymorphic virus
Rabbit virus
Resident virus
Spacefiller virus
Stealth virus

Can a virus physically damage my computer?

Almost all computer viruses and other malware are only capable of affecting the data on your computer and cannot physically damage your computer. However, there have been viruses that have been designed to physically damage computers or hardware equipment connected to computers. One of the most notable viruses capable of damaging hardware is Stuxnet, which was designed to target industrial equipment, like nuclear reactors.

When was the term "virus" first coined?

The concept of a computer program capable of reproducing itself was first mentioned by John von Neumann in his 1949 "Theory of self-reproducing automata" essay. Later, Fred Cohen in 1983 coined the term virus in a 1984 research paper as "a computer program that can affect other computer programs by modifying them in such a way as to include a (possibly evolved) copy of itself."

What was the first computer virus ever created?

The first computer virus, known as the Elk Cloner, was written by Rich Skrenta in 1982 who was a 15-year old high school student at the time. The Elk Cloner virus spread to other computers by monitoring the floppy drive and copying itself to any floppy diskette that was inserted into the computer. Once a floppy was infected, it would infect all other computers that used the diskette. A computer that was infected would display a short poem on every 50th boot.

How many computer viruses exist today?

An exact number of computer viruses in existence today is very difficult, if not impossible, to determine. In 2018, Kaspersky reported an estimated 187 million unique viruses or related threats, including viruses and threats for computers and mobile devices.

New viruses, either original or variants of existing viruses, are created nearly every day. Antivirus companies, including Kaspersky, Symantec, and Trend Micro, are updating their list of known viruses daily.

What is the full form of "virus" or what is it short for?

The term "virus" is not an acronym. When referring to an antivirus or antivirus (virus protection), the "anti" is a prefix that describes the program helps protect against computer viruses.

Antivirus, Hoax, Intruder, Logic bomb, Security terms, Software terms, Trojan horse, Vaccine, Worm, Zoo