Launched today by Google Jigsaw, Perspective is an application program interface (API) built on human reviewer ratings of hundreds of thousands of online comments. Starting from this human-determined baseline of what makes comments "toxic," Perspective then learns to automatically identify similar comments so they can be flagged by online publishers. Sites can use the Jigsaw tool in a variety of ways. For instance, Perspective can be used to flag questionable comments so human moderators can review them and decide whether or not to publish them. Google said publishers can also use Perspective to let readers view the potential impacts of their comments as they write them, or to sort comments by toxicity to give preference to less abusive remarks.