Users turn to these groups for career advice, upcycling belongings, parenting tips, and even to market their small businesses. Learning new thingsCassier Weiner is in more than 50 mostly hobby-based Facebook groups. Sarah Dahan, an online community strategist, said the root of a thriving community online and offline is maintaining a consistent value system. Facebook doing its partJonathan Twombly runs a real-estate business through his Facebook group "Multifamily Investment Community," which has about 12,000 members. "Facebook groups are very underutilized by people my age," Kim said.

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