sentences:  Since user reviews can be posted next to advertising, when people read the reviews, there is a chance that they will also see advertising beside the review, which may possibly lead to a sale or at least result in positive exposure.This benefits the advertiser.Since it is possible to "track readership" (of reviews and hopefully advertising) using Google's "AdSense service", it's possible for advertisers to pay for this exposure through Google to RateItAll, and it's possible for RateItAll to share some of these revenues with reviewers to encourage contributions.