What is a Virus?
A virus is a computer programs that can “self replicate” or copies itself and spreads from one machine to another. Typically, a virus is a small piece of software that piggybacks on real programs. For example, a virus might attach itself to a program like Word. Each time Word runs, the virus runs too.
A computer virus is a form of malicious software – also referred to as malware. The forms of malware that anti-virus solutions protect against include the following: Viruses – a small program that attaches itself to another program or document and replicates with the potential to cause damage. Worms – specifically engineered to make extensive use of e-mail to spread them rapidly. Trojans – programs that pretend to be something harmless but have a damaging or otherwise malicious intent. Zombies – programs that install themselves on PCs and remain dormant until an external event triggers them into action. This could do damage to your PC, steal your personal information and send it to an unauthorized e-mail account, or even open up access to your PC remotely.
A virus is a program that self-replicates, and they are written by people who want them spread as widely as possible. Some viruses, such as Anna Kournikova or love bug, require user interaction to self-replicate – usually this means clicking on an attachment – while others, such as Code Red, can trawl networks looking for computers with a specific vulnerability to exploit. All viruses clog up networks and slow down the performance of your PC, but many also have payloads, or code that triggers an action on the infected machine. These payloads can be anything from wiping your hard drive to emailing confidential documents to public newsgroups to installing a “Trojan horse” on your computer that allows hackers to access your data.
A virus is a type of program that can replicate itself by making (possibly modified) copies of itself. The main criterion for classifying a piece of executable code as a virus is that it spreads itself by means of ‘host file(s)’. A virus can only spread from one computer to another when its host file(s) is taken to an uninfected computer, for instance by a user sending it over a network or carrying it on a removable disk. Additionally, viruses can spread to other computers by infecting files on a network file system or a file system that is accessed by another computer. Viruses are sometimes confused with worms. A worm, however, can spread itself to other computers without needing to be transferred as part of a host file(s). Many personal computers are now connected to the Internet and to local-area networks, facilitating their spread. Today’s viruses may also take advantage of network services such as the World Wide Web, e-mail, and file sharing systems to spread, blurring the line be
