From the back of the book:
To Build the future… to Dare greatly… to take one's Place in the arena…
Life takes against a grander tableau in the New Era. Without an omnipotent Imperium that has already imposed order n everything, the act of every man, woman and child looms larger, has a greater impact. And when even seemingly small actions have large results, imagine the sort of effect a person can have when daring greatly. The course of civilizations can be changed.
In the New Era, entire worlds have died or fallen back into barbarism. These worlds need peoples to come make them live again, and leaders to them back into the light. Such people need to have a variety of skills: they must be explorers, the must be builders, they must be leaders. They must have the courage to take on the power of a raw world and emerge victorious. These explorers, these builders, these leaders have a name. They are called World Tamers.
The World Tamer's Handbook brings to Traveller: The New Era a new arena in which to adventure: the ragged border of civilization, the realm of the unknown on a thousand worlds that do not know the light of civilization. World Tamer's Handbook provides material to create Survey campaigns in which characters push humanity's knowledge out into the Wilds, Bootstrap campaigns in which characters lift low-tech populations out of barbarism and Colony campaigns in which characters found and lead expeditions to repopulate entire worlds.
In order to do this, World Tamer's Handbook provides rules on colonial economics and infrastructure which allow players and referees alike to understand what makes a colony run, and what decisions need to be made to ensure success. These rules are not only useful for the campaigns in the book, but can ve used to flesh out societies in any Traveller: The New Era campaign or adventure.
In addition, expanded rules on world generation allows referees to create the details needed by players conducting detailed survey operations in advance of the colony transports.
Finally, additional design sequences expand on the information contained in Fire, Fusion & Steel to allow the design of black powder weapons, bow weapons an low-tech ground transportation.
A world can be a big, rough, wild place, but no world is too big, too rough or too wild for characters bold enough to be called world tamers.