Tezos Nomenclature

The following is adapted from this Agora post by Tezos Co-founder Arthur Breitman. As noted in the post, there is no official body that can authoritatively set Tezos' nomenclature, but the following is recommended:

Tezos

Used somewhat interchangeably, either as a noun or an adjective to designate:

• An open-source project and software (as in, “contributing to the Tezos codebase”)
• A peer-to-peer network of nodes maintaining a blockchain (as in “a Tezos node”)
• The specific Tezos chain with the most economic relevance (as in “the Tezos chain”). Typically, this would be today the chain whose millionth block had hash BKtC4QCWoF73kxLj773vFpQuuwrnye6PS7T1aM3XEPvFXiQbNu7.

Tez

A unit of the cryptocurrency native to a Tezos chain (e.g. “I sent you 2 tez”). Tez is invariable. It is not capitalized (except at the beginning of a sentence or when you would otherwise capitalize a noun). “I sent you 2 tez” and not “2 Tez”.

XTZ

XTZ, tez, or ꜩ (\ua729, "Latin small letter tz") is the native currency of Tezos.

“XTZ” is an ISO-4217-compatible code for representing tez on the most economically relevant Tezos chain. Unless there is a very specific reason to use an ISO code for it, the term tez should be preferred. Situations where the ISO code might be useful typically involve accounting systems, exchange rates with other currencies, and anything that might need some sort of standardized code. Generally speaking, as of the day of this post, “XTZ” is vastly overused in situations where “tez” or even “Tezos” would be appropriate.