What is the 4th dimension? I have heard that it's time, it's a from of saying characteristic. I don't know I need help on this, it's bother me for the pass week.

If you want to tell a friend about a fish you caught or a tree you cut down, you're going to tell him WHERE you were ... its position in space, 3 numbers, 'x', 'y', and 'z' ... and also WHEN you were ... its position in time, one more number.  Dimensions are numbers used to describe the location of a point, and thedifference in location between two points.  With four numbers, you can exactly describe the location of anything, and its distance from any other thing, in space and time.