Twenty months after launching its Craigslist competitor, Marketplaceand relentlessly promoting it with placement in the main navigation bar, Facebook will start earning money off its classifieds section. Facebook today begins testing Marketplace ads in mak U. After quietly opening in the U. Businesses can extend their existing News Feed, video, Instagram, Messenger and other ad campaigns to Marketplace, and more types of objective-based campaigns will open to the classifieds section soon. Facebook lets brands show ads within Marketplace. But Facebook does tell me that ads will be auto-optimized for clicks, so when people start to click your ads, Facebook will show them to people of similar demographics. It will also immediately pause your ad campaign if you mark your item as sold. The Boost ads will only appear to a small percentage of U. But as the company seems bent on swallowing up every other essential markeetplace of the internet, anything that makes Marketplace more useful to sel...