Hello,
I have an oral presentation to do about viruses and i wonder how antivirus softwares (like avast) can be free ?
I’ve done some searches on the internet but i didn’t find anything.
Does someone know the answer ?
(sorry for my english, i’m french)
i look forward to your reply
With many products the free version is a marketing hook to establish a supplier contact with you. The free product is often deficient in important respects, and this is then pointed out to you in the hope of enticing (or worrying) you into buying the paid version.
The avast! model has traditionally appeared somewhat different. The free product is competent and quite full featured, and certainly in avast 4 was openly advertised as such. The corporate goal was nominally to prevent the spread of malware by ensuring that free protection was available to all. The paid version had more features that it was still obviously hoped would attract you.
A perhaps unexpected result of this approach was that many users (myself included) would at times upgrade to the paid version simply to give avast some money in return for the years of free service.
The avast! free product remains very full featured, however the avast! marketing material seems now (personal opinion only) to be leaning toward suggesting that it isn’t adequate for many user needs. (Without a firewall it plainly isn’t)
Thank you very much for your answer mag,
I understand now, it will help me 
Isy, it’s a freemium model: free + premium product.
There are some interesting texts in the blog.
You can Google avast freemium and you’ll find something, for instance, http://business.financialpost.com/2010/08/24/avast-summit-partners-invests-in-freemium-antivirus-provider/
This entry from the avast! blog is interesting:
Avast! Free Antivirus, Version 5.0: “…nothing short of a miracle”
https://blog.avast.com/2010/01/19/avast-free-antivirus-version-5-0-“…nothing-short-of-a-miracle”/
When I was at school I had to find my own sources - in BOOKS!! :o