In the mercurial world of social media, where a new platform is anointed the hottest every year or so (Snapchat’s the reigning queen bee), it’s impressive how much user devotion 12-year-old Facebook inspires. In January, the site had 1.59 billion monthly active users.  That’s great news for marketers: Facebook is still the most brand-friendly social channel—allowing marketers to post embedded links, host e-commerce pages, tailor the reach and breadth of advertising, and easily develop and manage business pages and listings.  And because Facebook is so well-trafficked, it has actually become its own search engine. The site’s content, including business listings and reviews, shows up prominently in Google search results. But keeping up with users’ demands means it’s always adding and upgrading tools and features.  Improvement is Facebook’s goal,