Mozilla and Opera offer free Web Browsers. how do these companies gain from this?? how do they make money by offering free Web Browsers??
Donation, Sponsor and advertising on their site. For instance, Firefox is sponsored by google that is why google pay $1 per user install Firefox browser.
Here is a quote of referral ads And 1usd is payed only for usa and canada(?) traffic, for other users it is 10c!