It started as Tote, an app for comparing online stores offers. Despite the funding, the app wasn't successful, but one feature stood out. The users liked the "Favorite option that allowed them to save their favorite pics.
Later, the app would send push notifications when the saved items would get cheaper.
The app's founders noted this little fact and decided to build a new app that would allow users to browse pictures and store their favorite ones on their profiles. They also created categories. Their users often searched for products with the use of common category names ("ackets." "jeans." and so on).
They were different from other social media apps because they focused on people's interests - not on their statuses. The founder, Ben Silberman, promoted the app by himself. He would go to coffee shops and other places where people usually meet, and then ask them to check out his new app. He then observed what they liked about it (and what they didn't like). The First 3,000 users appeared within 3 months