Pinterest Inc. hit the demographic jackpot after it launched four years ago, becoming the digital scrapbook du jour for blushing brides, arts and crafts enthusiasts and home decorators hunting for ideas and inspiration.

About 42% of online U.S. women use Pinterest, according to a Pew Research survey released this month, a coveted audience with enormous spending power. Among its social peers, only Facebook Inc.’s site boasts a higher percentage of the online U.S. female audience.

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