The viruses are the malicious programs that can be forbidden, detected, and removed by a software called antivirus. These soft wares are not limited to the viruses but they also remove the worms, spywares, ad wares, Trojan horses, and many other malicious programs.
The antivirus soft wares use a lot of strategies to work. The antiviruses are signature based, which means they look for a pattern of executable code to detect a new program. Once this pattern is detected, the anti-virus starts to compare the programs with this signature and filters the files that match.
The antiviruses use a lot of identification methods. The most common is signature based detection which compares the contents of a file to the signature database. Since the viruses attach themselves with the files so the antivirus catches the whole files and the pieces of viruses. Due to the introduction f new viruses every day this signature database soon outdates. These anti viruses keep updating themselves with the internet that are updated with the upcoming viruses. The heuristics detection identification method is the one that identifies the viruses that keep changing their forms with the interaction with other viruses and files. These viruses grow into other mutation versions. The antiviruses detect these files and remove them. The rootkit detection is the identification method that is administered to acquire administrator level control over the computer. These rootkits change with the operating system functions. It may also temper with the antivirus and making it useless for catching the malicious programs. It is also difficult to remove as much as it may require the whole operating system reinstallation.