A virus in computer world is effectively a program that may infect other programs by copying itself onto the program and making the host program unusable.

The computer viruses are tiny software programs that are inherently designed to spread from computer to computer and in most cases interfering with the normal operations of the computer.

The effects of a virus can be:

• Deletion of system files

• Corruption of user data

• Wiping of Hard disk drive

• Corruption of executable software, etc.

Normally viruses spread through local network, USB drives, Optical Disks, email attachments, etc. Once a piece of software is infected with the virus, it itself will start infecting other files on the computer and/or other computers in the network.

There are two major types of viruses: resident and non-resident viruses. Non-Resident viruses have two different modules; a finder module and a replicator module.

The finder module finds the specific files that the virus can infect and once such a file is found, the replicator module is called by the finder module and then the virus gets replicated.

Resident virus does have both the finder and replicator module, but the replicator module is not called by the finder module. The replicator module is loaded onto the memory of the system as and when it boots and the module is called each and every time the operating system is called to process some data.

Virus infections can be removed through free or commercial antivirus tools or software available in the market.