Deep web is the part of the Internet that is not indexed by search engines. It requires the user to use a TOR-aware browser in order to enter the deep web. The usual goal of those who pay money to buy bulk user data has something to do with identity theft activities. The price of a typical single account is a mere $1. The buyer can retry the user credential in other websites like social media and public forum login. The moment the credential becomes outdated and unusable, the buyer can go back to the same deep web site and demand for a replacement identity.”]
Source: https://hackercombat.com/bulk-stolen-user-information-sold-at-a-bargain-in-the-deep-web/