It is common in technical writing to abbreviate complex technical terms by combining the first letters. The resulting abbreviations are often called acronyms. Editorial guidelines for the RFC series generally require expansion of these abbreviations on first occurrence in a title, in an abstract, or in the body of the document.

The RFC Editor attempts to keep the use of abbreviations consistent and to point out conflicts to authors. For this purpose, we have built the abbreviation list below. This list contains abbreviations appearing in RFCs and often reflects discussions with authors, WG chairs, and/or ADs. There is no claim of completeness. Note that some abbreviations have multiple expansions.

Some abbreviations are so well known that expansion is probably unnecessary. The RFC Editor exercises editorial judgment about whether a particular use of one of the “well-known” abbreviations requires expansion. (For example, strict adherence to the expansion requirement can lead to impossibly ugly titles.) In the following list of abbreviations, those that are usually (but not necessarily) treated as “well known” are marked with asterisks. However, since there are so many different abbreviations and there is a range of knowledge among RFC readers, we tend to expand abbreviations in case of doubt.

Finally, this list includes some terms that look like abbreviations but are actually fixed names for things, and hence cannot and should not be expanded. These are noted as “No expansion” or “Do not expand”; they are also marked with asterisks.

Note: Names of resource records do not need to be expanded (e.g., NAPTR).