What is a Fourth Dimension?

[xCross]

What is a fourth dimension?? Is this time or any other space coordinate??

[Orion1]

The fourth dimension is time.

Reference:
Fourth dimension - Wikipedia (http://en.wikipedia.org/wiki/Fourth_dimension)

[pixel01]

Different from 3 other dimensions, time can not go backward.

[gendou2]

Dimensions, like space and time, don't "go" anywhere.
There is an arrow of time, which tells us in which direction overall entropy is expected to be greatest.
In general relativity, time is treated as just another dimension.
Also, in quantum physics, the laws of nature are the same forwards and backwards in time.
Some physicists argue this speaks to a weakness in our understanding of time.

[atyy]

There are 3 space dimensions and 1 time dimension. In everyday life and in Newtonian physics, time is completely separate from space, and everyone has the same time. In relativity, time and space become mixable - what is time for you could be space for me.

[pixel01]

There are 3 space dimensions and 1 time dimension. In everyday life and in Newtonian physics, time is completely separate from space, and everyone has the same time. In relativity, time and space become mixable - what is time for you could be space for me.

Yeah, this is true in some analytical instruments which I have to work with. When you don't have space, time can be fractmented into very small parts and they are treated such as spaces. One example is : the Ion Trap vs the QQQ.
By the way, who can show me a point can be moved in the 4 dimension both forward and backward in time direction?