AdEx (ADX) is an open, trust-minimized protocol & stack for digital advertising that reduces ad fraud, malvertising and protects user privacy. It originated in 2017 as a decentralized ad exchange for digital advertising, and later evolved into the full-stack solution it is today. The AdEx protocol facilitates trading of advertising space/time, as well as the subsequent verification and proof that it actually occurred. Essentially, it covers all interactions between publishers, advertisers and end users. The protocol combines traditional peer-to-peer technology, cryptography and blockchain.