- Did you mean the NPC named "Whisper"?
- /whisper <player_name> <message>
- /w <player_name> <message>
- /tell <player_name> <message>
- /t <player_name> <message>
All four commands are functionally the same.
PST is an acronym for Please Send Tell. It originated from older online games, MUDs, and MMORPGs such as EverQuest, which used /tell to send private messages to other plays. In World of Warcraft, it has come to be frequently mistaken for the interjection 'psst', due in part to the game's common use of /whisper. The latter meaning has become fairly widespread amongst players, occasionally leading to debates and disagreements over its proper grammatical usage (for example, "LFG, PST" versus "LFG, please pst me").
Patch 3.3.5 (2010-06-22): Instead of whispering someone, players will now tell them something.
While function of this has not changed, it was simply reworded in the new chat frame.