Dimensions refers to units used for measurement of space. that can be used to determine the quantity of a point in space as well as the volume. As a point in space can be completely identified in terms of a three dimensional axis system, and volume or quantity of space can be completely measures in terms of three dimensions of length the three dimensions are length, breadth, and depth.
However as per some advanced scientific principles space itself changes with time, and therefore time is also needs to be specified to location of a point in space. As per this thinking time can be considered to be a fourth dimension of space.
Einstein's theory states that the universe would have four dimensions (3 of space and one of time). Our everyday experience of life clearly shows us that space is three-dimensional (so we perceive it) and time is considered the fourth dimension.
However, there are modern theories in science (still unproved experimentally) which suggest that the universe has more dimensions, additional dimensions of space. Einstein tried to discover and formulate a "theory of everything", to unite the four fundamental forces which exist. Through this theory, Einstein has considered that he could explain the entire Universe. He has failed to build such a theory. Yet another theory, which has stood for the title, was developed later and it was called "String Theory". This theory predicts the existence of a universe, composed of 11 dimensions.
Even though mathematically it is easy to extend the idea that there are more than four dimensions, the question is whether all these have physical meanings. According to the studies of Albert Einstein, time and space are closely linked.
In earth, it is 4 D.
But in outer space, it is 6D
Do you wonder why it is 6 D.
It is because - East, West, North, South, Up & Down.
Am I correct.