How to normalize a data structure

The benefits of normalization

Since a normalized database has more tables than an unnormalized database, and since each table has an index on its primary key, the database has more indexes. That makes data retrieval more efficient.
Since each table contains information about a single entity, each index has fewer columns (usually one) and fewer rows. That makes data retrieval and insert, update, and delete operations more efficient.
Each table has fewer indexes, which makes insert, update, and delete operations more efficient.
Data redundancy is minimized, which simplifies maintenance and reduces storage.

Each normal form assumes that the design is already in the previous normal form.
A database is typically considered to be normalized if it is in third normal form. The other four forms are not commonly used and are not covered in detail in this book.