1NF, 2NF, and 3NF are the first three types of database normalization. They stand for first normal form, second normal form, and third normal form, respectively. There are also 4NF (fourth normal form) and 5NF (fifth normal form).

First Normal Form (1 NF) 
Second Normal Form (2 NF)
 Third Normal Form (3 NF) 
Boyce Codd Normal Form or Fourth Normal Form ( BCNF or 4 NF)