ULD Kiel Nokia Siemens Networks JANET(UK) CDT Privacy is a concept that has been debated and argued throughout the last few millennia. Its most striking feature is the difficulty that disparate parties encounter when they attempt to precisely define it. In order to discuss privacy in a meaningful way, a tightly defined context is necessary. The specific context of privacy used within this document is that of personal data in Internet protocols. Personal data is any information relating to a data subject, where a data subject is an identified natural person or a natural person who can be identified, directly or indirectly. A lot of work within the IETF involves defining protocols that can potentially transport (either explicitly or implicitly) personal data. This document aims to establish a consistent lexicon around privacy for IETF contributors to use when discussing privacy considerations within their work. Note: This document is discussed at https://www.ietf.org/mailman/listinfo/ietf-privacy