Traveller is set in the sectors controlled by the Imperium, a remote central government possessed of great industrial and technological might.
Due to the sheer distances and travel times involved it is unable to exert total control at all levels everywhere within its star-spanning realm. As a result, the Imperium allows a great deal of autonomy to its subject worlds beyond the central Core systems.
Here on the frontier, in a sector called The Spinward Marches, extensive home rule provisions allow planetary populations to choose their own forms of government, raise and maintain armed forces for local security, pass and enforce laws governing local conduct, and regulate commerce (within limits). The Imperium asks for respect for its overall policies, and for a united front against outside pressures.
Defence of the frontier is mostly supplied by local indigenous forces, stiffened by scattered Imperial Naval bases manned by small but extremely sophisticated forces.
Conflicting local interests are often settled by force of arms, with Imperial forces quietly looking the other way, unable to intervene in any but the most wide-spread disputes, which threaten the security or the economy of the area.
The Imperium also maintains the Imperial Interstellar Scout Service, equal in stature to the Imperial Navy and Army, whose duties include exploration of and beyond the Imperial frontier, on-going mapping and surveying of Imperial territory, and the maintenance of interstellar communications through its express boat network.
The IISS maintains bases and waystations on many worlds in order to facilitate its mission.
Moving within the safety of the Imperium are the merchantmen. Whether free trader or megacorporation bulk tranport, tramp liner or luxury cruiser, it is trade and commerce which is the life blood of the Imperium.
Your character, _______, has just mustered out having served __ terms in the ______.
You are on ________.
Adventure awaits.