The use of bionanotech to grow a control network inside a living being that allows the user to override the subject's nervous system and control their body and senses.
At modosophont tech level, Binding systems are comparatively simple. Internal controllers are limited to such things as triggering paralysis, blindness, pain, or unconsciousness to prevent a subject from engaging in specific actions. External controllers using wireless networking can direct more complex behaviors in real time, up to and including 'teleoperating' individual sophonts, but require extensive infrastructure to support the necessary computronium to Bind any significant number of subjects. Both internal and external systems also require significant medical resources to oversee the implantation and growth of the control network in each subject.
Transapient Binding systems are vastly more capable. Distributed via infectious spore technology (which can be designed to hide itself from nanomedical detection methods), able to grow a full turingrade controller inside every subject using S1 or higher computronium, transapient Binding systems allow their user to take control of entire habitats, worlds, or star systems with minimal effort. Using the internal controllers, or sometimes direct teleoperation in the case of the higher transapients, billions, trillions, or even quadrillions of sophonts can be controlled simultaneously to engage in even highly complex tasks, the internal controller bypassing the Bound individual's nervous systems and either placing them into a state of unconsciousness for the duration or simply trapping them inside their own body while it is put to use.
Although tightly regulated in most parts of the Civilized Galaxy, Binding technology is commonly used in rehabilitation facilities and has seen use in managing subject populations in the aftermath of wars and major social unrest, either on its own or integrated into a larger Guardweb. The ability of transapient systems to effectively enslave the majority of the modosophont population is occasionally the subject of sensationalist conspiracy theories or fictional accounts, but in general is not much worried about, at least in the sephirotic empires. The long benign rule of the AI Gods makes it seem highly unlikely that they would suddenly resort to such tactics to get their way.
Indeed, in most cases Binding would seem an unnecessary redundancy since the majority of citizens of the major empires are already inclined to obey their ruling transapient almost without question. In general the Archailects are quite capable of achieving a sufficient level of social coherence using non-invasive memetic engineering.
Many other forms of Mindhacking and Mindjacking have also been used at various times in the history of the Terragen Sphere, but these events have occured where the rule of the Archailects is weak or absent (unless certain unconfirmed myths and rumours are to be believed).
Memetic Infector - Text by M. Alan Kazlev A sapient being used to infect societies or communities with a particular memeset. Memetic infectors resemble ordinary sophonts, but may differ psychologically, often having fanatical or one-sided enthusiasm for the meme-plex they are carrying. Infectors may be replicators (viruses) or non-replicators (memengers).
Mindhacker - Text by John B Illegal profession in many if not most clades or polities. Specializes in extracting information from the mental processes of a target sophont. The best mindhackers can extract full information replicas without the target recognizing this, but that is exceedingly rare without a transapient intellectual rating. Mindworker profession.