Space-time continuum

The space-time continuum, or time-space continuum, (PROSE: Engines of War) simply refered to as the continuum, (COMIC: Follow That TARDIS!, PROSE: The Book of the War) was the term for the continuous set of coordinates created by the whole of space added to the whole of time.

Nature
The Time Vortex was the structure of the space-time continuum. (PROSE: The Crystal Bucephalus) Holes in the space-time continuum, outside conventional of time and space, could lead to other universes. (PROSE: The Pit) The "foam-structures of the continuum" were weaker around the node points of history, meaning that intruders into the universe from outside, such as the Yssgaroth, would usually try to break through at those points. (PROSE: The Book of the War)

N-Space, which was the prime universe according to the Doctor, comprised eleven dimensions, including those comprising the space-time continuum. (PROSE: Parasite) The Doctor's TARDIS herself stated that she was an "eleven-dimensional being" that existed across all space and time, (TV: The Doctor's Wife) while the Fifth Doctor referred to the ship as having an internal continuum. (AUDIO: The Butcher of Brisbane)