Short answers, pulled from the story.
Memory is the faculty of the mind by which data or information is encoded, stored, and retrieved when needed. It is the retention of information over time for the purpose of influencing future action.
The first precise experiments exploring sensory memory were conducted by George Sperling in 1963 using the partial report paradigm. These experiments showed that the capacity of sensory memory was approximately 12 items but degraded very quickly within a few hundred milliseconds.
Craik, F. I. M., and Lockhart, R. S. published Levels of processing: A framework for memory research in 1972. This research shows that memory is better when encoding emphasizes deep aspects of a stimulus such as meaning versus shallow aspects.
In 1956, George A. Miller conducted experiments showing that the store of short-term memory was 7 plus or minus 2 items. Modern perspectives estimate the capacity of short-term memory to be lower, typically on the order of 4 to 5 items.
The hippocampus is essential for learning new information to the consolidation of information from short-term to long-term memory. It receives input from different parts of the cortex and sends its output out to different parts of the brain.