Akamai Meta Cloudflare qlog provides extensible structured logging for network protocols, allowing for easy sharing of data that benefits common debug and analysis methods and tooling. This document describes key concepts of qlog: formats, files, traces, events, and extension points. This definition includes the high-level log file schemas, and generic event schemas. Requirements and guidelines for creating protocol- specific event schemas are also presented. All schemas are defined independent of serialization format, allowing logs to be represented in various ways such as JSON, CSV, or protobuf. Note to Readers Note to RFC editor: Please remove this section before publication. Feedback and discussion are welcome at https://github.com/quicwg/qlog (https://github.com/quicwg/qlog). Readers are advised to refer to the "editor's draft" at that URL for an up-to-date version of this document. Concrete examples of integrations of this schema in various programming languages can be found at https://github.com/quiclog/ qlog/ (https://github.com/quiclog/qlog/).