BAT (Basic Attention Token), a token for a decentralized ad exchange. It compensates the browser user for attention while protecting privacy. BAT connects advertisers, publishers, and users and is denominated by relevant user attention, while removing social and economic costs associated with existing ad networks, e.g., fraud, privacy violations, and malvertising. BAT is a payment system that rewards and protects the user while giving better conversion to advertisers and higher yield to publishers. We see BAT and associated technologies as a future part of web standards, solving the important problem of monetizing publisher content while protecting user privacy.