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Antivirus software is like a guard that identifies and destroys computer viruses on your system before the virus can cause any serious damage to the system such as deleting a files or formatting your system. Antivirus software can also protect your system from harmful programs such as Trojan and worms.

Computer Virus is a program written that can attach itself to a file. When the infected files are opened, the virus infests other files on the system, and also spreads to other systems with the help of infected files. Viruses damage the system by deleting the files on the system, increasing the file sizes, or automatically formatting the system.

Different types of computer viruses

Different types of computer virus can infect the system and slow down the working process of a computer.

Boot Viruses

The Boot Viruses infects the boot sector and copies the virus code in the boot sector of the disk, this ensures that the virus is always executed and located in the memory when the system starts. Once in the memory, the boot virus infects other files and floppy disks inserted in the drives, and spread it to other system. For example, the Boot virus Tequila infects all the exe files on the system and also infects the master boor record of the hard disk.

Polymorphic Viruses

A person can keep on changing the way he looks to disguise himself this make is difficult to trace a person. Similarly, Polymorphic Viruses are coded in such a way that they infect a system and change their signature before infecting the next system. This, the antivirus software finds it difficult to identify this virus, as Polymorphic Viruses looks different after every infection. For example, the virus Hare copies the virus code in the boot sector of the hard disk and infects floppy disks inserted in the system, it also changes the virus’s signature frequently to prevent antivirus software from detecting it.

Macro Viruses

Macros are blocks of codes written to automate frequently performed tasks and embedded in a program file such as a word document or an excel worksheet. When a macro having the virus code is executed, it infects the files on the system. For example, the Love Bug Virus erases files on the infected system and emails a copy of the macro virus to contacts from the uses address book.

TROJANS, WORM and Spywares are some others types of Virus which can infect the computer and slow down the working process.