A computer virus is a computer program that can copy itself and infect a computer without permission or knowledge of the user.
*Computer viruses are small software programs that are designed to spread from one computer to another and to interfere with computer operation.
*Computer virus is a harmful software program written intentionally to enter a computer without the user's permission or knowledge. It has the ability to replicate itself, thus continuing to spread. Some viruses do little but replicate, while others can cause severe harm or adversely affect the program and performance of the system. A virus should never be assumed harmless and left on a system.
What do computer viruses do?
*Through the course of using the Internet and your computer, you may have come in to contact with computer viruses. Many computer viruses are stopped before they can start, but there is still an ever growing concern as to what do computer viruses do and the list of common computer virus symptoms. A computer virus might corrupt or delete data on your computer, use your email program to spread itself to other computers, or even erase everything on your hard disk.
*Computer viruses are often spread by attachments in email messages or instant messaging messages. That is why it is essential that you never open email attachments unless you know who it's from and you are expecting it.
Computer viruses also spread through downloads on the Internet. They can be hidden in illicit software or other files or programs you might download.
Viruses can be disguised as attachments of funny images, greeting cards, or audio and video files.
There are different types of viruses which can be classified according to their origin, techniques, types of files they infect, where they hide, the kind of damage they cause, the type of operating system, or platform they attack. Let us have a look at few of them.
1. Resident Viruses- which is permanent an dwells in the