As we all learned in high school, one of the most basic properties of space is its extension, also called its dimensionality. The world in which we work, pay taxes and take vacations is a three-dimensional one. The intricate gyrations of a ballerina or a gymnast tell us that no matter how we might move, we never 'turn a fourth corner' and find ourselves moving along a new direction through space. And then there's Time. A strictly three-dimensional world is pretty boring.
Nothing happens in it.
Suppose you tell your friend that you will meet her at the entrance to the Washington Monument. Your well intentioned instructions will help her narrow your location in the universe to a six foot cube of space at a particular point on the surface of the earth. But unless you also say when to be there, the instructions are useless. Time is a vital fourth coordinate or dimension to our world. Now, much like the frozen images captured on a photograph.