NF means normal form
1NF: Rules are following
There are no columns with repeated or similar data
Each data item cannot be broken down any further.
Each row is unique i.e. it has a primary key
Each field has an unique name
2NF: Rules are following
The table must already be in first normal form
Non-key attributes must depend on every part of the primary key
3NF: Rules are following
The table must already be in second normal form
There are no non-key attributes that depend on another non-key attribute