Learning

You usually think of 'learning' as acquiring new knowledge or a new skill set. That's the harder type of learning to study. It builds upon the easier-to-study types of learning, like classical conditioning. These are easier to study because they are either responses to single stimuli or simple associations requiring only one or two stimuli, not interesting new knowledge. First, let's master these simpler types and then move onto more complex learning.

Non-associative learning
This is a change that occurs solely because of repeated exposure to one particular stimulus (as opposed to associating one stimulus with another stimulus or behavior).

There are two types: habituation and sensitization.

Habituation occurs when an animal was producing a response to a stimulus, but learns that there is neither a positive or negative consequence to doing so. It then decreases its response more and more, until it ceases to respond to the stimulus. You can think of habituation as the boy-who-cried-wolf effect.

Sensitization is the opposite--increased exposure to a stimulus causes increased response.

Associative learning
This is a change that causes an organism to associate a stimulus with another stimulus, or a stimulus with a behavior.

There are two types: operant conditioning and classical conditioning.

Operant conditioning occurs when a reward or punishment is used to reinforce a behavior. An example would be spraying a dog (punishment) when it barks (behavior).

Classical conditioning occurs when one stimulus is repeatedly presented with another so that when one is presented, the organism predicts the second. The famous example of this is Pavlov's dog, where the dog has paired the bell with the food and begins to salivate when he hears the bell. It is different from operant conditioning because there is no behavior that the dog is learning to do in order to obtain the food, but it knows that the bell shortly precedes the food.

The learning you want to know about
Unfortunately, it seems as though there is little well-organized information about this available on the web. You can click around Wikipedia or anywhere else, and if you have a good idea for how to organize this information, we'll add you as a contributor!