A primary key is a unique value for a record in a database. Every record must have a primary key to avoid duplicate entries and database errors.   [The Digital Classroom Resource].  

A technique used to “steal” or redirect traffic that would normally be directed to another website in search engine results. [The Digital Classroom Resource].  

A device shaped like a pen that works with touch screens or graphics tablets. Users use it to interact with the GUI of the Operating System. [The Digital Classroom Resource].