Facebook and Twitter thrive on what users do — where they travel, who they’re hanging out with, which cat videos make them LOL. But Pinterest, that other social-network titan, thrives on what users want: each page on the three-year-old platform is filled with beautiful images of clothing, gadgets and more that have been “pinned” from all over the Internet. As CEO Ben Silbermann puts it, the site is “helping people get inspired and live out those aspirations.” But it’s also, by proxy, reshaping how brands, users and more-established networks define social. Although Pinterest’s early buzz has waned, its emphasis on wanting over liking is still fueling growth — some 20 million people pin every month — and has hooked a user base that buys significantly more than those on Facebook, LinkedIn, Twitter and Tumblr, according to several studies. As a result, big names like Lowe’s and Whole Foods have made the platform an integral part of their branding strategy, and industry analysts speculate that Facebook may soon introduce a Want button.