Keyword advertising, or sponsored search, is one of the most successful advertising models on the Internet. One distinctive feature of keyword auctions is that they enable advertisers to adjust their bids and rankings dynamically, and the payoffs are realized in real time. We capture this unique...

This paper provides insights about when versioning is an optimal strategy for information goods. Our characterization of this class of goods is that variable costs are invariant with quality, including the special case of zero variable costs. Our analysis assumes a monopoly firm that has an...