The concept of the fourth dimension is quite a hard subject to wrap your head around.

We only observe our world in three directional dimensions, but theoretical physicists consider that extra dimensions could occur beyond our perceptive reach and one of those is the fourth dimension. It’s a postulated spatial dimension additional to those determining length, area, and volume.

So we already know that we can’t see or precieve this fourth dimension and researchers also tried to explain time travel through fourth dimension but it’s still seems fictional. If we can’t use the fourth dimension to time travel, and if we can’t even see the fourth dimension, then what’s the point of knowing about it? Understanding these higher dimensions is of importance to mathematicians and physicists because it helps them understand the world. String theory, for example, relies upon at least 10 dimensions to remain viable [source: Groleau]. For these researchers, the answers to complex problems in the 3-D world may be found in the next dimension — and beyond.

Although it is a quite a hard subject and tough to wrap your head around, this incredible High-School student does a wonderful job of explaining the fourth dimension.