Hi. I’m an old user of avast! Free Antivirus 5.0 and I have a question regarding the number of Definitions.
Every time my virus database is updated… I notice that the number of definitions decreases. At one time avast! showed me having 3,000,000+ definitions, and now it’s down to a little under 2,000,000 definitions. No other Antivirus program has done this so i’m not sure if this is normal or if virus families are being integrated… Could a developer or expert please tell me what’s going on?
see here my friend
http://blog.avast.com/2010/09/06/spring-cleaning-in-our-virus-database/
This makes sense… Thank you for showing me this.
no problem, glad to be of help 
In fact others have done this as well, i can name Comodo and BitDefender as such, but others do it as well, it’s just that not all have definitions number visible, so users don’t even know it happens.
I find the “numbers game” fairly meaningless anyway, since there’s no industry-wide standard (or even general agreement) for how to count number of items you’re protected against. Taking as an example minor variations in a specific malware, some manufacturers will count the variations as additional items while others don’t.
They all do similar things. I used Norton AV for years and if you took the time to read the release notes of the DB updates, you always saw things being added and other things being deleted. With new generic signatures that can detect many variants of the same malware, the number of definitions will be less.
I for one am ultra, mega happy that my Virus Database Updates went from on the average 20 minutes … down to now around 5 minutes. YES!