See also Category:Dimensions
In general, dimensions are defined by the number of coordinates needed to isolate any point within an object.
Thus for example, a line is one-dimensional (length), a circle two-dimensional (length, width), and a cube three-dimensional (length, width, height). These are known as spatial dimensions and are the most common points of reference in terms of the understanding of dimensions and the basis of what is commonly known as a three-dimensional world.
However, if the object is capable of movement, then the concept of a fourth-dimension, and thus a fourth-coordinate is required. This fourth coordinate maps the point's location at any given moment in time. This is why time itself is often referred to as the fourth-dimension. Although it is important to note that a single coordinate of time implies a linear progression of time, wherein the object can only exist in one place at any one given moment.
Most Spatial-Temporal Beings are only capable of experiencing and perceiving the world around them in those four dimensions. They are capable of moving through and perceiving space, and capable of experiencing and linearly moving through time.
However, it is known that other, sometimes called higher, dimensions also exist. These other dimensions are defined by levels of existence reached by travel through means other than the three dimensions of space, or the single, linear dimension of time. These dimensions are difficult to fully define by human standards or science, but it is known that such cosmic phenomena as sub-space and super-space exist in or on those other dimensional levels.
It is also known that certain beings exist on higher dimensional levels as well. These beings, known commonly as Extra-Dimensional Beings perceive and experience reality through more than the standard four-dimensions and thus often possess unusual abilities and powers related to that aspect of their existence. The full nature of their existence remains to be defined, but their actual existence is known.
- Wikipedia Article on Dimension