Paid placement, where advertisers bid payments to a search engine to have their products appear next to keyword search results, has emerged as a predominant form of advertising on the Internet. This paper studies a product-differentiation model where consumers are initially uncertain about the...

In sponsored search advertising, advertisers bid to be displayed in response to a keyword search. The operational activities associated with participating in an auction — submitting the bid and the ad copy, customizing bids and ad copies based various factors (such as the geographical region...