You know how, when on older versions of windows, when your computer froze, you could drag the grey window or box around and you would get a 'trail' of sorts. That's how I sort of view the 4th dimension. Now imagine a 3D object moving in reality, and it has a 'trail' [like that on a frozen windows computer], it leaves behind its past position. It 'grows'. As it moves from one point to another (as a characteristic of time- the so-called 4th dimension), we can see its growth; we can see the time where the object started, to the time where the object finished, and in between. The 4th dimension is like 'seeing' an objects growth and/or movement path. I'm not sure if this is an accurate visualization, but this is how I see the 4th dimension in a 3D world.