Pay-per-click (PPC) is an advertising model that lets advertisers place ads on an advertisement platform and pay the host of the platform when their ad is clicked. The goal of the ad is to lead the user who clicks to the advertiser’s website or app, where the user can complete a valuable action such as purchasing a product. Search engines are popular host platforms as they allow advertisers to display ads relevant to what users are searching for. Advertising services like Google Ads and Microsoft Ads operate with real-time bidding (RTB), where advertising inventory is sold in a private automated auction using real-time data.