Three types of memories are stored so they can be used later. Procedural memories are largely unconscious and are developed through procedural or statistical learning. Episodic memories encode the details of what happened on particular instances. Important, stressful, or traumatic life events are typically stored in episodic memory, but these memories are not reliable. Semantic memory includes all other types of learning, including facts and the structures we use to organize facts. Semantic memories are dynamic as well; as vernacular and slang phrases enter the lexicon, these become part of one’s semantic memory, but they will fade and change as the terms fall into disuse.