When most people hear politicians or newscasters speaking of a "trillion dollars," or read about such in any media, the concept of size is not adequately conveyed. I would bet most people think in terms of powers of ten, and assume that a trillion is 10 times more than a billion, which is ten times more than a million. Which, of course, is not even close to reality.
The top image depicts a million dollars in $100 bills. It's as much money as many people take home after taxes in a lifetime. The stack of $100 bills is surprisingly small for a million dollars; you could pick it up.
A billion dollars is not 10X as big or 100X as big. A billion dollars is a thousand millions. For the image it is depicted stacked on pallets.
Similarly, a trillion dollars is not 10X or 100X a billion. It is a thousand billions. In the image the human figure is standing at the lower left. And the pallets are stacked two high.
That's a trillion dollars.
Full credit to this link for the very useful graphic. (via)