Its also funny to look at the diagram of all the possible combinations of pennies - You would assume that you would know which one is correct intuitively - Because we use them in our everyday lives. When I look at the diagram with a friend, neither of us could guess the correct penny design.
Short term memory and long term memory are what have been classified as the the two types. STM is more fragile and is used in everyday tasks, etc... There are billions of units that make up our LTM - They are memories of the past. Looking at the three main areas of memory is interesting - I had never thought about it before. - for arbitrary things, for meaningful relationships, and for explanation. I had never thought about memory this way, but putting it in these terms makes sense.