Alliance safe worlds were usually remote worlds discovered by scouts working for Alliance Support Services. After discovery, Alliance teams would survey the planet to expose its hidden dangers, and set up settlements with basic supplies and farming equipment. Some remote worlds settled before the war, such as Sanctuary, also functioned as safe worlds for the Rebellion. These planets usually held only small, primitive settlements, since larger populations making frequent use of advanced technology were harder to hide from the Galactic Empire. Most safe worlds had populations between two and forty thousand, with the main economic activity being subsistence agriculture. Many of them had trouble with their scarce available foodstuff, and resorted to advanced Anomid technology (growth stimulator, preservation units, etc.) to maximize their possibilities. Some of them became prosperous enough to export cloth, food, and even minerals and fuel to the Alliance: but the more prosperous the safe world, the more likely it was to be discovered and conquered by the Empire.
Rebel safe worlds were populated by supporters of the Alliance who could not or would not take an active role in the Alliance. This included injured and retired members of the Alliance Military, political dissidents, sworn pacifists, exiled anti-Imperial politicians, and the families of Alliance officials and soldiers. Knowing that their families were on a safe world helped the morale of Rebel soldiers and starship crewmembers, who could be assured that their families had some measure of protection from Imperial reprisals. For this reason, the locations of safe worlds were the Rebellion’s most closely guarded secrets.
Small populations of Imperial prisoners of war were also found on Rebel safe worlds. These prisoners were kept on a different continent from the rest of the population. These penal colonies were given supplies and farming equipment, and occasionally visited by medical teams in heavily-armed vessels, but otherwise left to their own devices. The possibility of these prisoners escaping was slim, since they were thousands of kilometers from Rebel settlements, and had neither weapons, nor ground transport, nor long-range communications.
Other planets were home to major Alliance military facilities, and had planetary governments which openly supported the Rebellion. Though civilian supporters of the Alliance lived freely on Mon Calamari, and the Alliance established long-term military installations on Yavin 4, Hoth, and Arbra, such worlds were generally not classed as safe worlds—probably because they were too obvious as targets for the Empire.