Telepathy

Telapathy is a form of silent long distance communication that is one of the most important parts of the larger field of psionics. Telepathy is unique in that it relies on directly transmitting thought from one person to another, and is perhaps the closest that humanity has ever come to truly instantaneous communication. However, telepathy is not a universal ability for humans, and is in fact quite rare, with most of those capable of it being members of the psionic human subspecie, and even there while common, is not a universal skill. For those who are not pisonic, there is the capability of receiving telepathic communication, though without proper training and ability information received is vague, often limited to simple commands or feelings being transplanted from one person to another instead of a more directly understandable feeling.
Telepaths have a wide array of means of transmitting those thoughts. The simplest, and easiest for the telepath is directly linking minds between two telepaths and 'speaking' to one another that way. Such linked people can communicate at extreme range, on a planetary level even, and it is believed that if a psion theoretically had centuries to train they could in theory communicate over interstellar distance, faster than light, without the use of an ansible. This ability has not however been displayed in practice however. Telepaths can also use their gift on other, non-psionic peoples, though this requires a telepath to expend considerably more energy for lesser results. These abilities can be used to implant emotions, commands, or other simple direct forms of communication. With greater effort, a telepath can conduct a mental assault, in effect 'communicating' pain and suffering upon a victim. They can, in theory be used on other psions, though psionically gifted people are often trained in preventing intrusion upon their mind by unwanted guests.