What is a virus - computer :: Computer Science

What is a computing device virus - computerWhat is a VIRUS virus (computer), self-duplicating computer program that interfereswith a computers weightyw atomic number 18 or operating remains (the basic parcelthat runs the computer). Viruses ar designed to duplicate or copy themselves and to avoid detection. Like any other computerprogram, a virus must be executed for it to function-that is, it mustbe located in the computers memory, and the computer must then followthe viruss instructions. These instructions argon called the freight rate ofthe virus. The pay load up may disrupt or change data files, divulge anirrelevant or unwanted message, or cause the operating trunk tomalfunction.Computer viruses activate when the instructions-or executablecode-that run programs are opened. Once a virus is active, it mayreplicate by various means and tries to stain the computers files orthe operating system. For example, it may copy parts of itself tofloppy disks, to the computers hard dr ive, into countenance computerprograms, or it may attach itself to e-mail messages and string out acrosscomputer networks by infecting other shared drives. Infection is oftmore frequent in PCs than in professional mainframe systems becauseprograms on PCs are exchanged primarily by means of floppy disks,e-mail, or over unregulated computer networks.Viruses operate, replicate, and deliver their payloads only when theyare run. Therefore, if a computer is simply attached to an infectedcomputer network or downloading an infected program, it will notnecessarily become infected. Typically a computer user is not likelyto knowingly run potentially harmful computer code. However, virusesoften trick the computers operating system or the computer user intorunning the viral program.Some viruses have the aptitude to attach themselves to otherwiselegitimate programs. This attachment may occur when the legitimateprogram is created, opened, or modified. When that program is run, sois the virus. Viruses can also lodge on portions of the hard disk orfloppy disk that load and run the operating system when the computeris started, and such viruses thereby are run automatically. Incomputer networks, some viruses hide in the software that allows theuser to log on (gain access to)Types of VIRUSThere are five categories of viruses parasitic or file viruses,bootstrap sector, multi-partite, macro, and script viruses. parasitical or file viruses infect executable files or programs in thecomputer. These files are often identified by the extension .exe inthe name of the computer file. File viruses leave the contents of thehost program unchanged hardly attach to the host in such a way that thevirus code is run first. These viruses can be either direct-action orresident. A direct-action virus selects one or more programs to infect