More than 450 million people visit buy-and-sell groups on Facebook each month, Mary Ku, director of product management, wrote in a blog post. Still, Facebook has historically had issues with getting commerce features off the ground, in part because users see the site as a place to catch up with friends, not shop.
Facebook won't make any money off Marketplace because it's leaving buyers and sellers to transact however they wish, which can be done off the site.
Starting today, people can get to it via a "shop" icon at the bottom of their mobile applications.
A desktop version of the feature is due to launch "in the coming months".