Poshmark has carved out a niche that feels like window shopping on a phone instead of the search-to-buy purchasing experience you get on Amazon. People follow each other’s virtual closets full of clothes for sale—often pre-worn items with a mix of boutique items bought wholesale—and share items they find interesting. It’s a social network of 60 million people that’s a combination of influencers and your friends, akin to Instagram or Pinterest. The difference is: Everything you see is for sale.