Tristero is a fictional postal service featured in Thomas Pynchon's novel, "The Crying of Lot 49." It represents an underground communication network that operates outside the official postal system, symbolizing alternative means of connection and information dissemination. The concept of Tristero is tied to themes of conspiracy and the search for meaning in a fragmented world. It is associated with the mysterious symbol of the W.A.S.T.E. system, which stands for "We Await Silent Tristero's Empire," suggesting a hidden society that challenges conventional structures and norms.