A computer virus can be created maliciously by anyone who wants to cause harm to computers or systems. They are hidden pieces of code that ride with other programs or applications and once activated they propagate like wildfire. Typically, viruses can be found in a document or software that is downloaded from the internet or distributed via email. Many countries consider it to be illegal to create and distribute computer viruses.
In the world of computer viruses, there are several varieties that can infect a machine in different ways. Some depend on a program to begin their work however, others are completely independent and can attack multiple systems without the need of an host. Computer viruses that utilize a host program in order to infect computers are commonly called worms, but those that do not employ this method of infecting through other programs are referred to as viruses.
Certain viruses can infect a system immediately upon entry, whereas others are inactive and only become active when the user executes the code. The first computer virus was developed in 1974, and it behaved much like a biological virus by rapidly multiplying itself and causing harm to the system. One example of an extremely destructive virus is the Stuxnet virus specifically designed to destroy computerized centrifuges used to enrich the uranium.
It is not for the weak to attempt this process. However it is a fun and interesting method of testing your skills in computer programming languages and systems. If you’re willing to take the time and effort you can find a variety of sources that will guide you through the process of creating an infection.