Viruses and Anti-virus software.

*Viruses
Virus is malicious program that requires a host and is designed to make a computer system sick, just like real virus. Generally their three types of viruses.
1. File infectors
2. Boot sector viruses
3. Micro viruses

*Most of the viruses are spread by e-mail attachment.

*The following characteristics of computer virus are :

• It is able to replicate.
• It is activated by external action.
• Its replication ability is limited to the virtual system.

It requires a host program as a carrier.

*Damage that viruses cause

Main objective of virus is to make your system unstable and harm your data.

• It can destroy file allocation table (FAT) and leads to corruption of an whole system.
• It can create duplicate file.
• It can cause system to hang so that it does not respond to any keyboard or mouse movement.
• It can destroying parts of programs.

* Virus prevention 

Virus prevention is not a difficult task. You need to be extra care of Your computer.

• Never use a CD or any removable media without scanning.
• Always scan files downloaded from the internet or the other sources.
• Never boot your PC from floppy.
• Use licensed software.
• Make a regular backups.
• Keep antivirus software up to date.

*Anti-virus software
Antivirus software is a computer program that detects, prevents and take action against virus or harmful malicious program. There are many types of Anti-virus softwares such as -:
1. Microsoft security essentials
2. Quick heal
3. McCafee antivirus etc.

*What Anti-virus software does?

• It performs periodic scans of every file in the computer.
• It detects viruses and take action against it.