How true it is ?

I have AVG free antivirus downloaded and working fine ,Every day when i connect to interent, It says it is updating,I m little new to computers, what is the strory behind daily updating ? does that mean that every day they find new viruses ?

How true it is ?best antivirus software

It is estimated that 150 or more new virus's are launched every month. AVG has to update on a daily basis to keep you protected from them. Be glad they are doing it that often.

How true it is ?firewall

No, it doesn't it mean it's checking your computer if you have any, everyday.
Yes DUDE ... your are right .. New Viruses and Trojans and other threat are found every day .. so your anti-virus MUST update it's virus defn. database to keep you protected with the latest threats .. i use AVG too ..

so don't worry .. let it go and grab the latest updates

hope my answer helps
No problem, an antivirus needs regular updates.

Why?

Actually, the basic method of detecting a virus is by it's name (filename or command name) and it's code( the program, or you may say, the malicious code).

If you were to detect a file, what should you do for that?

I believe, you are going to search the web and gain information about that file, like you asked this question on yahoo answers.

Then probably, you should be able to decide whether that file harmful to you or not.

If it's harmful, engineers call it a 'Virus' else you may call it whatever.

Similarly, an antivirus like AVG or NORTON or McAfee, these all have a list of known viruses, there names, activities, methods, codes etc; which all help detecting a virus.

But from where do these antivirus engines know about a file (virus / useful / else) or get a list of such virus or their respective codes??????????

A suitable answer is UPDATES. That's why, your antivirus engine is regularly updating itself to protect you from recent threats.
Yes every day!