"The transition to being a publicly listed company will inevitably change the dynamic of Facebook, despite Mark Zuckerberg's insistence that his focus will remain on users and not shareholders, " said Andrew Tonks, a social media expert at the online marketing agency Koozai.

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Guys are also particularly active in online shopping, according to digital marketing agency iProspect.

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As part of a revamped business plan, the paper developed the Media Lab, a sophisticated digital agency that provides a full range of online marketing services to merchants.

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The system, developed internally at Linden Lab, has been adopted by online review site Yelp, event-planning site Eventbrite and digital-marketing agency Organic.

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The FDA said it has been reviewing online marketing practices of these companies and has reached out requesting that the companies speak to the agency about the claims.

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