A primary key is a value that uniquely identifies a database record or a row in a table. A primary key can be a single column or a combination of columns that have unique values for each record. A primary key ensures that each record can be distinguished from others and prevents duplicate data. For example, in a database that stores information about employees, the employee ID column can be used as a primary key for each employee record56. References := CompTIA IT Fundamentals (ITF+) Study Guide, 2nd Edition, Chapter 5: Database Fundamentals3; What is Primary Key? - Definition from Techopedia7