Computer Virus 

Virus is kind of malware. A program that is able to replicate itself. It makes modified and infected copies of itself and spreads over the system. It can also spread from one computer to another when it is sent with some files. It differs on one property: worm doesn’t need to be transferred as virus, it can spread itself. Unlike worms viruses must be a part of a host. Viruses are spread using e-mails, freeware, P2P file sharing systems and Internet.

Most viruses target is Microsoft’s operating system, because it’s the most popular. But viruses also can infect Mac OS, MS-DOS or AmigaDOS operating system. They also can infect various hosts. Parts of software or even some essential part of operating system are hosts for viruses. Virus inserts infected copy to the executable code or file. Most popular hosts:

• Application-specific script files;
• Boot sectors of disks;
• The Master Boot Record of a HDD;
• General script files;
• Binary executable files;
• Macros containing files;

The first virus is considered to be “Elk Cloner”. As there were no Internet in 1982, viruses were spreading using floppy disks. The greatest and the most dangerous virus was Chernobyl Virus which is still alive nowadays. Viruses were created for different purposes, but most of the reasons were malicious. Maybe only few of viruses were designed as researches. Although some viruses are really beneficial, because they remove other viruses. But writing and realising a worm or a virus is illegal activity.

Virus is a great danger for computer system, because it makes a lot of damage. Slower work of computer, error boxes, many crashed softwares, all this is a result of virus. One day you even may not be able to start you computer.

Nowadays most of anti-virus programs detect all viruses. It’s better to find anti-virus that warn user about worms or virus before infections. Update is essential part of software because the number of malware is growing everyday. Also real-time protection and scheduled scanner required. On- demand scanner has almost all anti-virus programs. It should also provide script blocking, e-mail protection and scanning, compressed files’ scanning. Some of anti-virus do not provide Trojan detection, spyware or ActiveX control, so in that case anti-spyware will really help. But note that there’s no such software that would give you 100% protection.