Reading does not come naturally; it is a difficult skill that must be acquired painfully. Once learnt, however, it is rarely, if ever, forgotten. So, we do not have to worry about forgetting how to read because the skill is firmly established in our long-term memory banks. Despite the retention of the reading skill in permanent memory, an entirely different type of memory is required during the active process of reading itself. While reading, we must retain a 'short-term working memory' for what has just been read. Some of the information acquired while reading may be committed to long-term memory but much is remembered for just long enough to enable you to understand the text. Memories must somehow be represented physically in the brain. Brain chemistry and structure is altered by experience, and the stability of these physiochemical changes can be associated with the retention duration of memory.