For the quarter, Google gained slightly, with 79.1% of all paid search marketing spend, versus 20.9% for Bing (Note: Other search engines like Blekko and Ask also get paid, but their shars are so tiny that putting them in might actually distort the comparative results, EF says.) That was up from 78.7% and 21.3%, respectively, in the fourth quarter of 2010.

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Supermarket loyalty cards record all their purchases, however revealing, and search engines note everything they have been looking for on the internet.

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Amtech pointed out in a research note that a test Google search of each of the top 10 best-selling prescription drugs at that time turned up a slew of ads for Canadian online drug peddlers like CanadaDrugPharmacy.com and CanadaDrugCenter.com.

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