A Federation is group of partially independent states, worlds to even whole galaxies, that united under one centralized (federal) government, giving up, in the process, certain rights and responsibilities, generally in foreign affairs. This make Federation is both a step-up (more connected) but also a setback (members are less freedom) than a Confederation. In Federation, self-governing status of the component polities, as well as the division of power among them and the federal government, are usually entrenched in constitution and cannot be altered by any unilateral decision of either party, the states or the federal political body. Hence secesionism, while still possible, is usually unlikely.