The first generation of online marketplaces, including eBay, Amazon, and Priceline, made it hard for sellers to discriminate. Transactions were conducted with relative anonymity. A user could negotiate a purchase without providing any identifying information until the seller had agreed to the deal. As a New Yorker cartoon famously put it, “On the Internet, nobody knows you’re a dog.” Except that platforms—and now their users—do know whether you’re black or white, male or female, human or canine. And the internet has recently been revealed as a source of discrimination, not an end to it: With their identities uncovered, disadvantaged groups face many of the same challenges they have long confronted in the off-line world, sometimes made worse by a lack of regulation, the salience photos give to race and gender, and the fact that would-be discriminators can act without ever personally confronting their victims. What happened, and what can we do about it? Read more at Harvard Business Review.