What is a virus?
This may seem to be a simple question, and in one sense the answer is simple. Unfortunately the original definition has been warped by the media to the point where the word is virtually without meaning. I prefer to use the term "Malware". What is Malware? Malware - short for malicious software - refers to any malicious or unexpected program or code such as viruses, Trojans, and droppers. Not all malicious programs or codes are viruses. For those of you taking A level the term malware is not yet in common use so avoid it in your exam papers be more specific.
Viruses, however, occupy a majority of all known malware to date including worms. The other major types of malware are Trojans, droppers, and kits. Due to the many facets of malicious code or a malicious program, referring to it as malware helps to avoid confusion. For example, a virus that also has Trojan-like capabilities can be called malware.
What is a Virus? A computer virus is a program - a piece of executable code - that has the unique ability to replicate. Like biological viruses, computer viruses can spread quickly and are often difficult to eradicate. They can attach themselves to just about any type of file and are spread as files that are copied and sent from individual to individual.
In addition to replication, some computer viruses share another commonality: a damage routine that delivers the virus payload. While payloads may only display messages or images, they can also destroy files, reformat your hard drive, or cause other damage. If the virus does not contain a damage routine, it can cause trouble by consuming storage space and memory, and degrading the overall performance of your computer. Some times the people who write viruses aren't as clever as they think themselves to be and viruses cause "accidental" damage.
Several years ago most viruses spread primarily via floppy disk, but the Internet has introduced new virus distribution mechanisms. With email now used as an essential business communication tool, viruses are spreading faster than ever. Viruses attached to email messages can infect an entire enterprise in a matter of minutes, costing companies millions of ponds annually in lost productivity and clean-up expenses.
Viruses won't go away. More than 60,000 have been identified, and 400 new ones are created every month, according to the International Computer Security Association (ICSA). With numbers like this, it's safe to say that most organizations will regularly encounter virus outbreaks. No one who uses computers is immune to viruses.
Whilst it is clear that some viruses are written my young computer "geeks", I hold the view that viruses are potential weapons. They should be treated more seriously than they are.