Viruses are in fact the computer programs that are written deliberately to attack the other programs or disk boot sectors. The point is to replicate whenever the program is executed or the infected disk is accessed. In a way, viruses are replicating entities. They can cause huge damage to a system resulting in the loss of precious date. There are certain types of viruses that may not harm you computer if coded properly. It is mostly observed that system damage due to the virus is because of the bugs found in code of the virus. That code makes a conflict with the system configuration and becomes the reason of system damage. Viruses focus on erasing files, formatting of drives; scramble the partition tables etc when the code is written intentionally to fulfill these purposes. The disastrous part of a virus is programmed to get executed when certain conditions are found. The conditions are usually set on a certain day, time or number of infections etc.
If we talk about the types of viruses present now-a-days, there are a variety of viruses used for different purposes. They are countless and with the passage of time they have been developed to break the shield of various anti-virus programs. All computer viruses are not meant to behave the same. There are several categories of viruses and malware. Malware is a kind of virus that is utilized to see the customer interest of website visits, and suggest products on the bases of user interest. They follow terminate but stay policy to notice the user interest.
Trojan Horses are the viruses that appear as the useful and desired functions. The activity of the Trojan horse may be advertised after its launching. The program performs other tasks secretly and user considers it as something else.
Boot sector viruses attach themselves to the first part of the hard disk. It is read by the computer upon boot up, while memory resident virus resides in the random access memory. Another commonly used virus type is Logic bombs/Time bombs. These are used to initiate at the specific date or at certain event in computer.
The anti viruses are the special programs and software that are coed to stop or completely destroy the viruses or evil software on the computers. These malignant programs may have entered the computer through disk sharing of internet. The purpose to design antivirus software is to design an application that could stay active and monitor the activity of every execution. It should have capabilities to make an alert for undesired running of programs. Antivirus was first used in the 80’s when a virus affecting all around the world was broken with Dr Solomon Anti Virus toolkit. This is possibly known the first antivirus. Today anti viruses have taken an extreme professional look. Their functionality is at much improved level and they are capable of providing real time scanning of data and prevent execution that is undesired. The automatic updates of virus definitions are provided by every antivirus program. Commonly used ant viruses are AVG, NOD32, Norton Antivirus, McAfee and kaspersky.