In April 2014, after building the Ethereum proof of concept with Jeff, Gavin published the Ethereum Yellow Paper, a technical specification of Vitalik’s white paper. While the white paper described the concept of Ethereum for the first time and included the basics on how it would work, the Yellow Paper dove into the exact details, the nuts and bolts of the Ethereum Virtual Machine, and served as a guide for any developer who wanted to build a software implementation.