What are normal forms in databases?

Normal forms are a set of rules and requirements for the structure of tables in relational databases, aimed at eliminating redundancy and anomalies during data updates.

The main normal forms:

• First Normal Form (1NF): all fields are atomic, meaning indivisible, and the table does not contain repeating groups.
• Second Normal Form (2NF): the table is in 1NF, and all non-key attributes depend fully on the entire composite key (if the key is composite).
• Third Normal Form (3NF): the table is in 2NF, and there are no transitive dependencies between non-key attributes.

Example: if an orders table stores information about the customer as well, then changing customer data requires updates in multiple places — this is redundancy. Separating into orders and customers tables solves this problem.

Normalization improves data integrity and simplifies maintenance.