Memory can be defined as the registration, retention, and recollection of experiences, thoughts, feelings, sensations, ideas, and knowledge. Human memory is complex.
Our brains need to remember important facts, future plans, vocabulary words, social norms, and how to perform routine tasks like making breakfast or following a bus schedule. To accomplish all this, the brain sorts through information, evaluates the importance of the information, stores away the information, and then retrieves it when we need it, often within seconds.
Memory problems can affect some or all of these processes. Some memory problems develop slowly, while others occur suddenly. Some types of memory problems are reversible, and others result in a gradual, permanent decline in memory.