Viruses are malicious applications which cause damage to the system of the computer, infecting important files and documents of the user. However, contrary to widespread guesses, the virus is not capable to cause physical damage to the computer and can lead a maximum to data loss.
Influence of viruses
Virus – the malware which is written with the purpose to do a certain harm to a program component of the computer. Distinctive feature of viruses is their ability to create automatic copies itself and to be implemented into the written program code of other applications working on the computer.
Viruses are written by malefactors for the purpose of violation of a data structure on target computers or servers. The malware can differ on the purpose, structure and activity in the operating system of the user. There are viruses which can be imperceptible to the user of the computer. However there are programs which are capable to put all operating system out of commission.
Stages of work of a virus
The activity of computer viruses has several stages. At the first (latent) stage the virus can be in a system, but it will not take any actions for destruction of files. Latent viruses can be imperceptible to the user and are easily calculated by means of antivirus software.
The virus can break only a program component which problem is in most cases solved at reinstallation of the operating system.
The malware which is in an incubatory stage begins distribution of code location which influences a program component of the computer. Some viruses send confidential information to malefactors or just send spam. During the work the virus begins to consume system resources that can also be noticeable for the user.
The active stage of work of the malicious application consists in continuation of sending the code and destructive actions. At this stage the removal of important files begins, system services vanish and functioning of network is broken. At the same time the computer processor, as well as other components, remain untouched.
Types of viruses
As work distinguish the boot sector viruses (which are started together with the operating system), file (activated at start of certain programs or files), file and boot, network (extending on the Internet and by means of network protocols) and document (strike only important documents on the user's computer).
Viruses can use an Internet channel for connection and sending data necessary for the program.
Contrary to popular belief, viruses are not capable to influence work of computer hardware, including the processor – components cannot break under the influence of a program component of the device.
Viruses do not work at the switched-off computer as are also programs which execution is impossible without software environment which the operating system is.