Explain Normalization of database

The database normalization is a measure of stability .
There are 4 forms of Normalization

First Normal Form or 1NF

To be first normalized a database table should not have a duplicate data . Reference for a data should be unique . Lets assume there is a table Customer and another table Customer_Details . Both having columns customer_name and customer_id . In this situation,if we want to change customer_name , it is required to be changed in both the columns of the table , therefore is not first normalized.

Second Normal Form or 2NF

If the table is in 1NF then we can check for 2NF.