As one of the most effective online marketing techniques, Comparison Shopping stands for shopping different sellers for prices, options, service etc. Comparison shopping is usually used by buyers to make the best choice enjoying a good bargain, while retailers apply it for knowing about the competition at the market.

Comparison shopping engines, or product/product comparison engines, are meant to compare the prices at various Internet stores. Thus, when a user is looking for some product, comparison shopping engines give a database with links to the advertisers. Most product engines don't sell products themselves; however, they earn commissions by providing the links to online stores. Basically those advertisers who pay more have more chances to attract prospects, as their ads are well positioned in the product comparison chart.

Such comparison shopping engines as Google Product Search, which represents a part of Google Base, don't charge the fee for placing the ads on their price comparison list. Other product comparison engines, like Shopzilla, PriceGrabber, Shopping.com and NexTag, use PPC and monetize via payment from their advertisers. Another comparison shopping business model implies the payment for including the retailer to the product comparison site.

Generally product comparison websites collect information either from sellers or via data feed files. Those retailers who want their products to figure in comparison shopping lists, provide the information about their prices and features. Another possibility is to transfer the data electronically.

As the comparison shopping technology is developing day by day, there are many ways to make money through it. Many online marketing specialists admit that comparison site optimization, i.e. increasing the site's prominence by optimizing prices, titles and overall content, has become critically important for a successful comparison shopping business.

All in all, comparison shopping is a powerful marketing strategy, which is popular both among buyers and retailers. Most owners of product websites admit that comparison shopping can be a quite lucrative business, if you know how to use it.