Final answer:
Primary key attributes are unique identifiers used to establish links between tables in a database.
Step-by-step explanation:
Primary key attributes are unique identifiers that are used to establish links between tables in a relational database. These attributes are typically inserted as foreign keys in other tables to create relationships.
For example, let's consider a database with two tables: 'Students' and 'Courses.' The primary key attribute in the 'Students' table may be the student's ID, while the 'Courses' table may have a foreign key attribute named 'StudentID' that references the 'Students' table. By linking these attributes, you can establish a relationship between students and the courses they are enrolled in.