Memory is a complex set of abilities that enable people to learn and retain knowledge from experience. There are various types of memory. Procedural memory deals with knowledge regarding how to do things. In contrast, declarative memory deals relates to facts about oneself and the world. There are two types of declarative memory. Episodic memory relates to certain episodes and is contextually bounded, where as semantic memory refers to the knowledge regarding the world, and is not tied to any episode. Another important distinction is between short-term (small amount of information that is rapidly forgotten) and long-term memory. Short-term memory is also known as working memory. Empirical research on memory originated with the studies of Hermann Ebingaus (1850-1909), who demonstrated that higher mental processes could be subjected to experimental study. Subsequently, alternative approaches to studying memory has led to better understanding of human memory. Such approaches include the naturalistic methods, biological methods, neurosciences, and artificial intelligence. The memory could be divided into three hypothetical stages; encoding, storage and retrieval. Standard experiments in these areas include two stages; exposure to information, and a test stage. Further, experiments on memory could be classified as encoding experiments or retrieval experiments. Encoding experiments involve manipulation of factors during encoding stages where as retrieval experiments manipulate the retrieval factors. A third type of experiment called the encoding/retrieval paradigm manipulates both the factors. Memory is also affected by factors that are held constant.

Original acquisition is a crucial aspect in memory, and it has been documented that effective encoding leads to better recall. In addition, more meaningful information is better remembered, and imagery is better recorded as compared to verbal stimuli, which in turn is superior to abstract ones. The distinctiveness of the stimuli is yet another factor affecting encoding. In the retrieval process, strong retrieval cues play a crucial role in efficient retrieval. The encoding specificity principle plays a role, where the effectiveness of retrieval cues is affected by the degree of its match with the encoding of original event. Similarly, the context in which the event occurred is also a major factor affecting retrieval cues. There is also certain degree of interaction between encoding and retrieval as demonstrated by the state-dependent retrieval (cases of drugs, alcohol etc..). Various mnemonic devices aid the memory/remembering process. The link method and the loci method are some of the good examples. On the other side, forgetting (loss of information over time) is a phenomena focused frequently in memory studies. It has been shown that forgetting occur soon after learning with decreasing losses after time. Forgetting also could be affected by intervening conditions and interference. Erroneous memory is yet another focus area. Several factors has been attributed to this phenomena, including retroactive interference, presentation of related information, and imagination.