Long-term memory (LTM) is memory in which associations among items are stored, as part of the theory of a dual-store memory model. The division of long term and short term memory has been supported by several double dissociation experiments. According to the theory, long-term memory differs structurally and functionally from working memory or short-term memory, which ostensibly stores items for only around 20–30 seconds and can be recalled easily. This differs from the theory of the single-store retrieved context model that has no differentiation between short-term and long-term memory. Long term memory is an important aspect of cognition. LTM can be divided into three processes: encoding, storage, and retrieval.