We have to make sure to include highly relevant advertisements in the search results, at least 50% of the results should be ads. So there needs to be a marketpl

We have to make sure to include highly relevant advertisements in the search results, at least 50% of the results should be ads. So there needs to be a marketplace for buying/selling ads. We can't have a search engine that is only useful for finding the most relevant web pages for a given query. People love highly relevant advertisement in their search results.