Normalization

Normalization is the process of organising a relational database into tables in a way that reduces duplicate data and avoids update, insert and delete anomalies. Related data is split into separate tables linked by keys.

It is done in stages called normal forms: First Normal Form (1NF) requires atomic values and no repeating groups, Second Normal Form (2NF) removes partial dependencies on a composite key, and Third Normal Form (3NF) removes columns that depend on other non-key columns. Some systems deliberately denormalise for faster reads.