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Normalization is the process of reorganizing data in a database so that it meets two basic requirements: (1) There is no redundancy of data (all data is stored in only one place), and (2) data dependencies are logical (all related data items are stored together). Normalization is important for many reasons, but chiefly because it allows databases to take up as little disk space as possible, resulting in increased performance.
Normalization is also known as data normalization.
The three main types of normalization are listed below. Note: "NF" refers to "normal form."
The following three NFs exist but are rarely used:
The first three NFs were derived in the early 1970s by the father of the relational data model, E.F. Codd. Almost all of today's relational database engines use his rules.
Some relational database engines do not strictly meet the criteria for all rules of normalization. An example is the multivalued fields feature introduced by Microsoft in the Access 2007 database application. There has been heated debate in database circles as to whether such features now disqualify such applications from being true relational database management systems.