Virus

For Computer viruses are written with a malicious intent, so that they can damage to computer programs, applications and data in addition to spreading themselves. Viruses infect all computer software and computer behavior activities such as actively destroy data, and perform actions on storage devices that render their stored data inaccessible.
Viruses attack on computer software like data files, operating systems, application software, and e-mails. Computer hardware is not infected by any virus.
Various methods of infect computer software’s. When you download online common program like game or word process, virus infect all computer software because some viruses attach themselves to a common program such as a popular game or word processor. After that virus upload into memory and infect other software program in storage disk. If virus finds any program, it converts the program by adding the malicious code to the program. When you execute this virus infected program of software, it infects other programs and the cycle continues thereafter.
There are many types of computer viruses such as a boot-sector virus, macro virus, e-mail virus, etc.
If virus infected program get execute in boot sector then virus infects the all boot record on hard disks and floppy disks, which is used to start the computer. When the computer is turned on or restarted, the virus is automatically executed. An infected boot disk may stop the computer from starting up.
A macro virus is a macro or script that attaches itself to a file or template. When the file is loaded, the instructions of the macro or script are executed.
E-mail messages contain various type of virus, and move one email to another email account, usually replicate it by automatically mailing itself to many people in the e-mail address book.
Virus also infect all type of operating system like windows 98, windows XP, windows vista, windows 7.
There are several anti-virus software that can detect, identify, and remove these viruses. As a precaution against viruses, we should take the following actions:
Anti-virus software that can detect, identify, and remove viruses should be installed on the computer.
All information downloaded from the Internet or some unknown resource must be immediately scanned for viruses by using anti-virus software.
Any e-mail attachment that comes from unknown sources should never be opened.