A computer virus is a program, a special program compiled by humans. A computer virus is a set of computer instructions or program codes that the programmer inserts into a computer program to destroy computer functions or data. It can affect the use of the computer and can replicate itself.
Computer viruses are artificially created, destructive, contagious and latent programs that damage computer information or systems. It does not exist independently, but is hidden in other executable programs.
After a virus enters the computer, it may affect the running speed of the machine at first, or crash and destroy the system at worst; therefore, the virus brings great losses to the user. Under normal circumstances, we call this destructive program computer virus.
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 viruses can be divided into three types according to the existing media: boot viruses, file viruses and hybrid viruses; according to the link method, they can be divided into source code viruses, embedded viruses and operating system viruses. 3 types; according to the system classification of computer virus attacks, they are divided into viruses that attack DOS systems, viruses that attack Windows systems, 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 (which spread through the network, and some data carrying viruses are increasing ), email viruses, etc.
Computer viruses are recognized as the number one enemy of data security. Since 1987, computer viruses have received widespread attention around the world. Computer viruses were first discovered in my country in 1989. Currently, new viruses are developing in directions that are more destructive, more secretive, have higher infection rates, and spread faster. Therefore, it is necessary to learn the basic knowledge of computer viruses in depth and strengthen the prevention of computer viruses.
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