At its simplest point, a dimension is a plane of movement and/or existence. At present, four dimentions are known to humankind: length, width, depth, and time. We, as a species, are only aware of travel through the first three dimentions. It has been postulated, however, that our only secondary comprehension of time (through deduction rather than through innate sensing) might differ vastly from the dimentional comprehension of unknown, extraplanetary species.