Computer Viruses

How does computers get affected by viruses, What is the real cause for it? How does antivirus help?

I will give answer briefly. There are different types of viruses,of serveral formats. some may come in the form of .exe files and some in .jpeg formats, and some in .doc formats,....
Mostly viruses will come in the format of .exe files. these types are when we click these files these will start execute the code and affect the system.
Generally these will be written in TSR programming in C language.
Some viruses will replicate while each execution.the code inside will be written like that.
Antiviruses Role:
After booting automatically antivirus enables and first check in the Ram memory. Then if we manually do scanning for a perticular folder then it will scan each and every file for specic format.Each virus will have specific format in its code.Antivirus will check for that format. If it finds it will give Intimation and auomatically Delete that code.

I gave general details. Indepth Details i also have to search.

--suresh--

thanks a lot for your info........
if u get any details plz message