eli5 What is a Candidate Key? [Normalisation Process]

Question

I know it’s a basic question but I can find a simple answer.

Is it just multiple primary keys?

In: 19

Answer 1

Primary keys have all unique values. All keys eligible for being selected as primary key are called Candidate keys. For example in a school table Roll No, Registeration No, Student ID No are all candidate keys. You select one from them to be a primary key.