The Fifth Normal Form (5NF) is a concept in database theory aimed at structuring database tables to minimize redundancy and anomalies. The 5NF builds upon the previous normal forms, particularly the Fourth Normal Form (4NF).

In 5NF, join dependencies are taken into account. A join dependency occurs when two or more attributes in a table depend on each other, but not directly; rather, they are connected through another table via a join operation.

A table is in 5NF if it is in 4NF and does not have any non-trivial join dependencies. Trivial join dependencies are those that are already implied by the primary key or superkeys. Non-trivial join dependencies indicate an additional relationship between the attributes that is not determined by the keys.

Applying 5NF helps further normalize databases and optimize their structure, leading to better data integrity and consistency.