there is no such thing as a memory in the sense of some thing that can be seen, touched, or weighed. Memory is an abstraction referring to a set of skills rather that to an object. Neither is there a single standard for judging a good or poor memory. There are a number of different ways in which a person may have a good memory.
memory is generally viewed as consisting of there stages : 1. acquisition refers to learning the material; 2. storage refers to keeping the material in the brain until it is needed; and 3. retrieval refers to getting the material back out when it is needed. These three stages may be viewed as the 3 R's of Remembering: recording, retaining, and retrieving. retrieving is where many problems come. we cannot do much about retrieval directly; but since retrieval is a function of recording, we can improve it by improving our methods of recording.
memory consists of at least two different processes: short-term memory and long-term memory. short-term memory has a limited capacity and a rapid forgetting rate. its capacity can be increased by chunking, or grouping separate bits of information into larger chunks. long-term memory has a virtually unlimited capacity. short-term memory and long-term memory also differ in several other ways