Memory is most frequently characterized according to the duration of information retention (sensory, short-term/working, and long-term; see Figue7.2) and with respect to the type of information storage (declarative or explicit vs. nondeclarative or implicit).The latter classification is used in long-term memory. Each of these groups has characteristics and subgroups of its own. They are briefly reviewed here. For more detailed explanations and discussions of different types of memory.