What is a Computer Virus

What is a Computer Virus?

A computer virus is a type of malicious software program designed to be exucated on users machine without his/her knowledge which replicates it's code into other computer programs and files in order to steal, harm or completely destroy the user information.

Types of viruses in Computer

  1. Direct Action Virus
  2. Multipart Virus
  3. Resident Virus
  4. Overwrite Virus
  5. Browser Hijacker
  6. Macro Virus
  7. Web Scripting Virus
  8. Boot Sector Virus
  9. Directory Virus
  10. Polymorphic Virus
  11. Encrypted Virus
  12. File Infector Virus
  13. Network Virus
  14. Companion Virus
  15. Nonresident Virus
  16. Stealth Virus
  17. Spacefiller Virus
  18. Sparse Infector
  19. FAT Virus
You can get more detailed information on these viruses from voipsheild.

In addition to these type of viruses there are several other things that can harm your computer like worms, adware, malware, Trojan, and ransomware. A type of malware in cryptovirology that threatens to publish the victim's (users) data on internet or block access to it unless a ransom is paid is known as ransomware.

Examples of a Computer Virus

Disk full virus in C

You might have encountered a virus that increases the hard drive space suddenly whether it is windows 8, windows 10 or MacOS. One cannot find a reason for that, it all happens mysteriously. But this is because of a virus and we can also make using C programming language. Do not run this on your own system.
/* disk full virus in C */

int main()


 return 0;
The above program will make a self growing file which may grow indefinitely to make your hard drive look full.

Computer Virus Names

Here is a list of particular names of computer viruses which did serious damage to the networks worldwide.
  1. Melissa virus (1999)
  2. Love Letter/I LOVE YOU Virus (2000)
  3. Code Red (2001)
  4. Slammer (2003)
  5. Fizzer (2003)
  6. MyDoom (2004)
  7. PoisonIvy (2005)
  8. Zeus (2007)
  9. agent.btz (2008)
  10. Conficker Virus (2009)
  11. Stuxnet (2009-2010)

History of Computer Virus

Father of Computer Virus

Jon von Neumann was the first who gave theory of self-replicating computer programs in 1949. Jon used to gave lectures at University of Illinois about "Theory and Organization of Complicated Automata". His work was later published as "Theory of self-reproducing automata". In his essay von Neumann described how a computer program could be designed to reproduce itself. Jon Von Neumann is considered as theoretical father of computer virology and his design for replicating computer programs is considered as world's first computer virus.

Science fiction Appearance

In 1970 Gregory Benford wrote a story which describes a self-replicating computer program called VIRUS, if installed on a computer with telephone modem dialling capability, it randomly dials phone numbers until it hit a modem that is answered by another computer.

This was the first fiction appearance of a virus. Later in 1972, this fiction of virus was recalled in novels, When HARLIE Was One by David Gerrold and The Terminal Man by Michael Crichton, and became a major theme of the 1975 novel The Shockwave Rider by John Brunner.

First Working Examples of Virus

The Creeper virus was first detected on ARPANET, the forerunner of the Internet, in the early 1970s. Creeper was written by Bob Thomas at BBN Technologies in 1971. Creeper used the ARPANET to infect DEC PDP-10 computers running the TENEX operating system. Creeper gained access via the ARPANET and copied itself to the remote system where the message, "I'm the creeper, catch me if you can!" was displayed. The Reaper program was created to delete Creeper.

In 1981 Richard Skrenta, a ninth grader at Mount Lebanon High School near Pittsburgh wrote a program called "Elk Cloner" which was discovered in 1982 as the first personal computer virus to appear outside the single computer or lab where it was created. It attached itself to the Apple DOS 3.3 operating system and spread via floppy disk. On its 50th use the Elk Cloner virus would be activated, infecting the personal computer and displaying a short poem beginning "Elk Cloner: The program with a personality."

These were the main events in the history of computer viruses, if you want to know more detailed history the Wikipedia provides exactly what you want.