Nanotechnology was invented in the 22nd century, but at first it was used only in manufacturing and warfare. It took a further hundred years for Nanites to completely integrate with all levels of society, just like Computers and Artificial Intelligences did before. The exact date of appearance of the Angel Nets (as they were called later), or even origins of the name are hard to tell. As the 23rd century progressed, and more powerful Nanites and Artificial Intelligences appeared, nanospheres of the cities were more and more potent and integrated, from emergency life-saving to building maintenance to changing the local weather. By the end of the century they reached a level on which reshaping and creating goods "out of thin air" was easy - at least within reasonable limits, and for those who were entitled to such wishes, for example by the thickness of their wallets. But the Angel Nets tented not only to the wealthy, since civilization reached such heights of the energy output and efficiency that creating such basic, low energy level goods like clothes or furniture was almost costless. The very landshape of cities, from the deepest arcology shafts to the clouds above, was alive with unseen activity.