What is database normalization? What are normal forms?

Database normalization is the process of organizing data in tables to minimize redundancy and ensure data integrity. It helps structure data to avoid duplication and anomalies during updates.

Normal forms are a set of rules and criteria that a table structure must meet to achieve a certain level of normalization. The main normal forms:

• First Normal Form (1NF): all fields are atomic, meaning they do not contain repeating groups or multiple values.
• Second Normal Form (2NF): the table is in 1NF, and all non-key attributes fully depend on the primary key (excluding partial dependencies).
• Third Normal Form (3NF): the table is in 2NF, and there are no transitive dependencies between non-key attributes.

Further normal forms (BCNF, 4NF, 5NF) address more complex dependencies, but most applications are sufficiently normalized at 3NF.