The Travelers are a group of people with incredible wit and talent and are usually very unique to their own territory. This group believes in a natural fate-like theory that gives them the motto; This is the way it was meant to be. Any mortal hand that we know of does not pick the Travelers, and so far we have only determined that they are born and raised for the purpose of being a Traveler. For example, when Bobby was younger his "uncle" took him on expeditions and otherwise to prepare him for some of the things he would have to do as a Traveler. This was also the way it was for Loor and, as far as we know, Spader. There should be only one Traveler from each territory, and at the time when there are two Travelers, the elder of the two will soon die. The previous Traveler, however, is allowed a certain amount of time to train the new Traveler in ways of judgment and responsibility. The purpose of the Travelers is to save Halla from Saint Dane, who is also a Traveler. The Travelers have apparently been around for a very long time, but if this were always the case it would make Saint Dane ancient. All the travelers have special abilities. They can influence people's thinking, can recover from injuries that would kill any normal person, and in The Rivers of Zadaa, Bobby uncovers the Travelers' ability to bring people back to life, just by willing them to come back.
In The Quillan Games, Saint Dane claims that the travelers are not physical, corpreal beings, but illusions, and that is how they are able to use their "powers", how Saint Dane and Nevva are able to change form, and how the travelers are able to use the flumes. While Bobby does not fully accept this, it does answer many questions raised by fans of the series.