Cybernetics are advanced robotics or computer system, implanted surgically into a person's body and wired directly into their nervous system.
Cybernetics originally were most commonly used to replace lost biological parts, as a more effective prosthetic limb. But these replacement limbs came to be made faster, stronger, tougher and more reliable than flesh resulting in elective usage for sports, labour, military and many other applications.
Other types of implant are also widespread. Hearing implants, replacement eyes or vital organs offer the same utility as replacement limbs but similarly come in upgraded forms. Beyond replacement parts there are implants providing added functionality such as built in data storage for digital couriers, systems to run personal apps, or even implanted weaponry.
The process of installing cybernetics is always difficult, not in the least with the extensive surgery required. Learning to use a cybernetic limb is also part of the process, this is relatively straightforward with simple replacement parts but with implants that offer completely new functions the effort learning to use them can be immense.
Many elements of society reject the cybernetically enhanced transhumans in their midst, thinking them inhuman monsters. The inner city in particular sees elective implants as dangerous and a cause of Techshock.