The three types of references that you can include on a CV are professional, academic and character. Professional references or employment references are referees that can attest to your work history. Academic references are referees who have taught you in the past. Character references are referees who know you on a personal basis and who can speak about your values and character. Ideally, you should be able to provide at least one professional or work reference. But if you have none, an academic or character reference can suffice for non-senior roles.