A computer virus is a virus that can invade a computer system and

Computer virus refers to a special program with the ability to reproduce that can invade a computer system and lurk and spread in the computer, destroying the normal operation of the system.

Computer viruses are contagious, covert, infectious, latent, excitable, expressive or destructive. The life cycle of a computer virus: development period → infection period → incubation period → attack period → discovery period → digestion period → extinction period.

Computer virus classification:

• Computer viruses can be divided into 3 types according to the classification of existing media: boot viruses, file viruses and hybrid viruses;

• Can be divided into three types according to the link method: source code type viruses, embedded viruses and operating system type viruses;

• Systems attacked by computer viruses The classification is divided into viruses that attack DOS systems, viruses that attack Windows, system viruses, and viruses that attack UNIX systems.

Today’s computer viruses are constantly introducing new ones, including some unique new viruses that cannot be classified according to conventional types for the time being, such as Internet viruses (spread through the Internet, some carry viruses (increasing amounts of data), email viruses, etc.

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