/say to talk to people in front of you (this is default)
/party to talk to your party
/alliance to talk to your alliance in a 24-person raid
/shout to talk to everyone on the current map
/yell to talk to everyone in a large radius but not necessarily the whole map
/novice to talk in the novice network if you are in that

https://na.finalfantasyxiv.com/lodes...d/?category2=1