Encoding is the process of receiving information via neural stimulation. During the encoding process, the brain converts sensory stimulus into neural activity. The brain registers new information or sensation. Storage is the process of creating a neural record of the newly received information. Retrieval is the process of remembering the stored information. The degree to which the brain is able to retrieve depends on how the information was encoded and stored. Information stored in short-term memory is stored superficially; the retrieval period is limited to approximately 15 seconds. Information stored in long-term memory can be retrieved years after encoding and storage.