Puterspace, also refered to as the Matrix or matrix, was a form of virtual reality prevalent in the Earth Empire in the 26th century. It was accessed through a jack port installed on the back of the neck, or a wire crown for beginners, that linked the person with a puterspace deck.
Puterspace was made up of the communications network between all computers on Heaven and in its orbit. The data was easy to get into by wandering around in it, and individuals were able to create their own places within a matrix. Their virtual bodies also shaped to their desires. Computer viruses could destroy a projection of a person n Puterspace, and subsequently kill their body in the real world.
The Travellers created the Land Under the Hills, or "the Dreaming," which was their own domain within Puterspace and held the Great Wheel. Rather than use drugs, they entered this reality to achieve higher states of consciousness, hold meetings, and see glimpses of the future. (PROSE: Prelude Love and War) The Daleks could hack into Puterspace and create attack ships, but they weren't very good at it and were vulnerable. Trap software developed by the Rutans could reshape a matrix around a person based on their worse memory or nightmare, trapping them there. (PROSE: Love and War, AUDIO: Love and War)
The Doctor later trapped the Timewyrm within Puterspace. (COMIC: The Last Word)