Anti-virus software technology

To anti-virus software finds a virus is a malicious program that is what
Why is technology being used.
It is not very difficult actually.
Pattern matching method is a way to test and compare the files on the target database in which the code of the virus found in the past has been recorded.
This method was found virus can be considered as a true virus with high probability.
Can be identified from the damage and how the name of the virus, I should not be difficult disinfection.
But I can not find the other known viruses.
If a new type of virus has been identified that is required to quickly update the pattern file.
This is true of technology and anti-virus software maker.
The current anti-virus software and all the main pattern matching.
Then, in some viruses to change the shape every time.
It is called the virus mutating.
Pattern matching can not be applied in this case because, I will be determined by examining the structure of the program.
I want to determine whether the virus to see the movement of the program.
Not mean that you can confirm that it is a virus, in this way it is only deemed suspicious.
We will be eventually subjected to further investigation by the manufacturer, to determine whether the virus.
There is no doubt that the pattern matching is the most reliable anti-virus.
Therefore, anti-virus software is adapted to update the pattern file each time at startup.