Virus

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.

Which operating systems are susceptible to viruses?

All of the major operating systems can contract a computer virus. Whether you use 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.

How does a computer get infected with a virus or spyware?

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. Typically most computer viruses will 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. More sophisticated viruses like Stuxnet can cause physical damage.

Examples of computer viruses

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

Appending virus                                     Encrypted virus        Overwrite virus
Boot sector virus                                   Executable Virus       Polymorphic virus
Spacefiller virus, a.k.a. the Cavity Virus   MBR Virus                Rabbit virus
CMOS virus                                            Macro virus              Resident virus 
Companion virus                                    Multipart virus          Spacefiller virus
                                                         Non-resident virus        Stealth virus 

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 disk was. A computer that was infected would display a short poem on every 50th boot.

Why do people create viruses and malware?

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 anti-virus (virus protection), the "anti" is a prefix that describes the program helps protect against computer viruses.

Related pages

How do I remove a virus from my computer?
What are the top 10 computer viruses of all time?
How do I create a computer virus?
All other computer virus questions and answers.
Computer virus and information overview.