We are living in a world with 3-dimensional space: width, height, and length. A point is zero dimension; a line is one dimension with length property; a rectangle is two dimensions with width and height properties; a cube is 3D with width, height, and length properties.

So, how is the fourth dimension? Normally, we will use time for fourth dimension. Why? Now, if there is a point, with coordinate (x,y). Since it is a point, there is no length, width, or height, thus it is zero dimension. If the point is moving according to axis-y gradually with constant speed, and we record the point with time (t), then we plot the point into a graph, it will become a line as the right side of the image above. Therefore, zero dimension becomes one dimension.