What is Memory?

In Chapter 7, the main topic of discussion is "memory". Throughout history, there have been many different ideas of how memory exactly works. Memory has been said to work like such things as a wax tablet, a cage full of birds, a leaky bucket, a cow's stomach, and many other oddities.
Another way to think of memory is as a 3-stage model that consists of sensory memory, short-term memory, and long-term memory. Sensory memory functions are to sustain sensations for identification; it has a large capacity but a very short duration. Short-term memory functions are to do conscious work/think; it has a capacity of 7 +/- 2 "chunks", and the duration is just a little bit longer than that of sensory memory. Long-term memory's function is to tie together the past with the present; it has an enormous capacity and an essentially permanent duration.
Within long-term memory, there are many subcategories. Among these include explicit memory, implicit memory, episodic memory, semantic memory, and procedural memory. Each has a different function, and all have a long duration.