Human memory has both short-term and long-term components. To retrieve information from long-term memory, the memory must be prompted. To retrieve information from short-term memory, prompting is also necessary. Storage in short-term memory is temporary, and described items are chosen based on a perception of time, i.e., a sense of when an event happened. Items from short-term memory can be prompts for long-term memory. When executing a procedure that is stored in long-term memory, the current step of the procedure recorded in short-term memory prompts the long-term memory to provide the next step. This is known as “memory inertia.”