Data normalization is a process in which data attributes within a data model are organized to increase the cohesion of entity types. In other words, the goal of data normalization is to reduce and even eliminate data redundancy, an important consideration for application developers because it is incredibly difficult to stores objects in a relational database that maintains the same information in several places.
First normal form (1NF) An entity type is in 1NF when it contains no repeating groups of data.
Second normal form (2NF) An entity type is in 2NF when it is in 1NF and when all of its non-key attributes are fully dependent on its primary key.
Third normal form (3NF) An entity type is in 3NF when it is in 2NF and when all of its attributes are directly dependent on the primary key.