"Cyborg" is the classification given to any human, mutant, clone or otherwise intelligent, sentient biological being that has been enhanced with or received robotic and/or mechanical augmentations, such as a mechanical limb or robotic organ. According to The Bureau of Robotic Affairs, a being is only classified as a Cyborg if a significant component or portion of their body has been augmented. This classification is necessary to separate someone who merely wears glasses from someone who has had a limb or eye completely replaced.
Robotic augmentations have existed for hundreds of years. Historians generally regard Benito Mussolini as the first Cyborg in existence. In the confusion of the Gran Sasso raid of 1943, Mussolini's arm was damaged so badly it had to be replaced. German scientists were successful in creating a working, fully-functional mechanical limb for Mussolini, although it was very limited and clunky. Still, the success of the project gave German Chancellor Adolf Hitler a significant interest in the technology, and would later sign a decree that his own body would be augmented should the unthinkable occur.
The unthinkable would indeed occur year later, when Hitler was near-fatally wounded during the Operation Valkyrie bombing. The incident would rob Hitler of both his natural legs and his left arm, along with the left half of his face. After spending ten days in a medically induced coma, Hitler's body was successfully augmented with cybernetic replacements. However, the augmentation components were created in a fervent rush to save Hitler's life, and as such were poorly made and did not function properly. This left Hitler in a miserable, broken condition for the very short remainder of his life.
After The Atomic Eclipse of 1964 that destroyed the majority of humanity, augmentation technology experienced a prolonged blackout that would not end until sometime during the Reconstruction Era following the year 2105.
Today, the technology of cybernetic augmentations has improved dramatically. A census poll taken by The Coalition of United Human Unions shows that as of 2326, over 10% of the human population of Circuit Falls have received robotic enhancements in some way, shape or form. Usually to compensate for an injury or disability, but often just to "improve" their bodies in some fashion.