To understand how we learn, it is first necessary to understand something about how we think. Intelligence is fundamentally a memory-based process. Learning means the dynamic modification of memory. A system can be said to have learned if it is different at time t1 from the way it was at time t0. Under this kind of definition, even forgetting is a kind of learning. Learning means change--change that causes a system to act differently on the basis of what is contained within it. Human memories are in a constant state of dynamic modification.
Learning depends upon inputs. Each word you read and each sight you see changes your memory in some way. The role of memory is the interpretation and the placement of those inputs. Memory must decide what's worth keeping by determining what the meaning of an input is and where it fits in relation to previous knowledge it has already stored.
One commonsense but incorrect view of memory is that it is simply a warehouse where we keep our knowledge when we are not using it. This warehouse notion implies that learning is the stocking of memory with uninterpreted knowledge. The corresponding notion of remembering is that when we need a piece of knowledge, we go into memory and pull it off of the shelves. This notion is appealing but misguided. There are no alphabetically listed bins in memory. When I ask you to tell me an incident where your mother was mean to you when you were young, you don't look under M for mother or M for mean and run into information about moths located near by. Memory organization depends upon meaning and thus is organized in a way that might have you run into something about your father or something about punishment while you were looking for the incident I asked for. The way memory is organized has great importance for theories of learning.