A field identified in a record as holding the unique identifier for that record is called the:

The field identified in a record as holding the unique identifier for that record is known as the primary key. A primary key serves a critical role in database management systems by ensuring that each record within a table can be uniquely identified. It enforces entity integrity by preventing duplicate records and maintaining consistent relationships between tables.

In relational database design, the primary key is fundamental in establishing relationships with foreign keys in other tables, which are references to the primary key. This enables data normalization and efficient data retrieval. Furthermore, the database management system automatically indexes primary keys to optimize search performance.

While the term "key field" can be used informally to reference fields that serve important roles in identifying records, it does not convey the same specific meaning and rules as "primary key." Other terms like "primary field" and "unique ID" may be used in different contexts, but they do not capture the formal definition or functionality of the primary key in a database context. Thus, the accurate and recognized term for the unique identifier of a record is the primary key.