A professional reference is obtained from someone whose name you supply to a hiring manager at the reference-checking stage (or sometimes sooner) in your job search. These people will most likely be called, and they do not need to prepare a written statement.
How many? Three is standard. Occasionally you may be asked for as many as five.
Whom should you ask? Former managers who will speak well of you and your work are the best professional referees. They are familiar with your work, as well as how you handle feedback, your level of initiative, and your strengths and weaknesses as a team member. If you are early in your career these can be supplemented with non-managers as appropriate. For a first job out of college, supplementing your manager from the sub shop with a professor is fine. You could include a peer if you need to fill out the numbers, but no more than one (and this person should be a coworker, not a classmate—so, peer in the lab where you are both employed is okay, random guy who sits next to you in Chem, not so much).
How should you ask? It is best to ask directly and specifically. If you have any doubts, it is okay to approach a former manager and ask if they would feel comfortable being a professional reference. (What you actually mean is “will you say nice things” and in general the manager will know that, but if you are concerned, you can ask them directly if they would provide a positive reference for you in your job search.)
What information should you give your referee? Give your referee a copy of the job posting (or the link to the online posting) and your current résumé. This will help them know what parts of your duties for them will be relevant to the job you’re applying for, as well as what professional strengths you are highlighting in your application.
What will they be asked? The questions your references will be asked will vary, but in general they will probably ask about the quality of your work, your strengths and weaknesses, why you left, and whether they would rehire you. They may also ask about your reliability, how well you received feedback, and about how you worked in a team environment.
Do you need to include your current manager? No. In fact, it is standard procedure to ask applicants to give permission before calling their current manager for a reference. If your current manager is aware of your job search and supportive, though, definitely list them. A positive, current reference from a manager is very helpful.
When should you supply professional referees? When asked. There’s no need to put them on your résumé; the hiring manager or recruiting professional knows that you have referees and are prepared to supply them on request.
What information about the referees should you supply? Most applications will have specific instructions around the information that they want, and you should follow those guidelines. You can usually assume you need to gather some combination of the following: name, job title, organization, and relevant contact info. Phone and email is usually sufficient, but some online forms will also ask for postal mailing address, so be sure you have all that information at hand.
- Don't give a referee’s name without asking first.
- Don't misrepresent the role of a referee.
- Most importantly: Don't ask for a reference if you aren’t sure it will be positive!