Although the legal card pool evolved throughout the format, the widely-used community standard (and the one that GoatFormat.com follows) is to mirror the card pool used for US Nationals, SJC Seattle, and SJC Indianapolis, in which The Lost Millennium (TLM) was legal but Exarion Universe and Cybernetic Revolution (CRV) were not. It is worth noting that, historically speaking, there was no period of time at which Exarion Universe was legal but Cybernetic Revolution was not. For more detail on this subject, see Cybernetic Revolution (CRV) in Goat Format.
Today, the Yu-Gi-Oh! Goat Format is widely played online and in real life, mostly by people who were not competitively active during 2005 and want to try a new way to play Yu-Gi-Oh! However, there are some older generations of players who play to seek a more nostalgic experience. Goat Format is not supported by Konami and is maintained by a dedicated and passionate group of players who want to share the game that they love with others.
We at GoatFormat.com consider ourselves a part of that dedicated group. We wanted a central resource for everything that there is to know about goat format -- rules, decklists, tournaments, and strategy -- so we made one. We want to make it as easy as possible for you to learn more about your favorite format and share it with your friends. We do this so that the Yu-Gi-Oh! Goat Format community can grow and be enjoyed for years to come.
Now that you understand what the Yu-Gi-Oh! Goat Format is, we recommend also reading Why Play Goat Format?