Temporal difference (TD) learning is a prediction method which has been mostly used for solving the reinforcement learning problem.
Temporal-difference (TD) is a combination of Monte Carlo ideas and dynamic programming ideas. By approximating the current estimate policy, TD is related to dynamic programming. In addition, by sampling the environment according to some policy, it is related to Monte Carlo methods. Temporal-difference is a form of bootstrapping, as illustrated with the following example: Suppose you wish to predict the weather for Saturday, and you have some model that predicts Saturday's weather, given the weather of each day in the week. In the standard case, you would wait until Saturday and then adjust all your models. However, when it is, for example, Friday, you should have a pretty good idea of what the weather would be on Saturday - and thus be able to change, say, Monday's model before Saturday arrives.
The TD algorithm has also received attention in the field of neuroscience. TD(lambda) is created by R. Sutton. A good starting point to learn about temporal-difference can be found here.