Managers and Clients

These people have direct knowledge of your work, time management and workplace interactions. They can speak directly to your performance and the value you bring to a project. They are ideal references.

Generally, these are the only references a hiring manager will be interested in! Accordingly, you should try to ensure that all references you provide are from managers or clients as all others will have little or no value.

Colleagues and Coworkers

References from coworkers generally have much less value and many hiring managers won't consider them much, if at all. They are offered in cases where managers are not able or willing to give a strong reference. You'll want to disclose the reason you're providing colleagues instead of managers as a reference as this is a potential red flag for a candidate.

Giving colleagues you never worked with as reference will have negative value: they can't speak to your work at all and they might not even remember you.

Family, Friends and Significant Others

These are assumed to be biased and you should disclose the kind of relationship you had if you provide them as a reference. Because of the bias their reference is much less valuable. Only provide these if they managed you directly and you have no alternative manager to list.

Personal references are useless unless specifically asked for or in certain fields like childcare.

Value over Time

In most cases, the older a reference is, the less value it has. Potential employers are interested in your current work ethic, not what you did 10 years ago. In most countries, you won't list references from your current job to avoid disclosing your job search.

There are some exceptions of course. If you've changed industries and are moving back to a job in your previous field then older references have more value. References from high-profile companies can also have more value than more recent ones from less important companies.