Promoted Accounts are a type of advertising on social media platforms, particularly Twitter. They allow businesses and individuals to increase their visibility by appearing in the "Who to follow" section. This helps them gain more followers and expand their audience. When a user engages with a Promoted Account, they may see tweets from that account in their timeline, even if they don't follow it. This feature is designed to connect users with accounts that align with their interests, ultimately enhancing user experience while providing advertisers with a way to reach potential customers.