We are aware of the world around us as being composed of three spatial dimensions. Theoretical physicists of our time however have been dabbling with theories that postulate reality as being composed even higher dimensions. Einstein named "time" as being the fourth dimension in his "special relativity" theory. Later, "string theory" took up the number of dimensions to 10 and "M theory" pushed it up to 11. Imagining higher dimensions can be a bit unwieldy without walking through the steps that reach the higher dimensions.

I found a neat narrated animation at Imagining the Tenth Dimension website that starts from the 0th dimension and builds up to the 10th dimension with demonstrations of how it may apply and how we may perceive it. Check it out