Telepathy is the ability to communicate with the mind. Telepaths can send thoughts to non-supers and be able to read their mind. Tomorrow People can also experience people's memories through telepathy. Also, others can communicate with one another without being aware of others listening.
Telepaths with superior skill can push others out of their minds, causing the victim to suffer greatly. Errol has demonstrated this ability.
Telepaths with superior skill can also block others from reading their minds, causing the victim to suffer greatly.
Telepathy can advance to the point where it acts as a sensing medium. Some Tomorrow People can sense the residual energy from a teleport. Some can sense danger and sense specific people. Telepaths with enough skill can sometimes access the person their reading emotions. They can also use telepathy to track down the location of people.
The Founder displayed the ability to sense someone after they had left the area.
Charlotte Taylor displayed the ability sending out a psychic scream that dropped everyone in the room and prevented them from accessing their powers for a short period of time. How she does this is yet to be explained.