References
Other than interviews, one of the most challenging areas of a job search can be references. How to write a references page, references style, and references format are all common questions. First of all, you want business references (people you have worked for) as opposed to personal references (people you know personally, like friends, who can vouch for your character). The only time you would use a personal reference is if you had no business references (like when you start your first job). If you are just starting out with no business experience, you should use professors, teachers, or business people you have known for a while (such as a friend of your parent that has known you since you were a child).
Your last option would be your personal friends (if you have no professors, teachers, or business professionals to use as a personal reference). For any of these, you can put their name (after asking them) on a list of references or get a letter of reference or recommendation form them. Depending on the relationship, this would be referred to as a personal reference letter (or letter of personal reference) or a business job reference letter.
In case the person doesn't know how to write a reference letter or needs help writing a reference, the format for a reference letter is as follows: First paragraph says you are writing a reference for (name the person) and how long you've known this person. Second paragraph states good qualities about the person (always on time, efficient, courteous, dependable, etc.). Also give examples of how you realized these qualities (John worked for me for three years and was never late). Last paragraph should say "If you have any questions regarding this recommendation, please feel free to call me at 123-456-7890". Then close with Sincerely, and your name.
Provided you've been out in the workforce for a while, you should be able to come up with three business references. The best references are people who have actually supervised you (and will have nice things to say about you). Next, if there are supervisors you know at your company that you don't actually work for, but who are somewhat familiar with you and your work. Of course, you always ask a person if you can use them as a reference prior to doing so. It would also be helpful to get a letter of reference (also called a letter of recommendation) from each if possible.
The next source of business references would be any business people you have done work for (for example, if you have done any work on the side such as setting up a person's website, writing their resume, etc.). Next, you would go to coworkers - not the best reference because a reference should be a supervisor or someone you've worked for, but a coworker is better than nothing. Again, remember to ask them first (and pick someone who can be professional and say positive things about you).
If your supervisor is retiring, by all means congratulate them on that and ask if you could possibly use them as a reference in the future. A student just asked me that again the other day.
I would not suggest using your current supervisor as a reference because this will let them know that you are seeking another position (which could put your current job in jeopardy). For example, if lay-offs are required in the future, you might be high on the list. You should use previous supervisors as references instead.
You shouldn't use references that are very old if it can be avoided. Someone you worked for fifteen years ago probably isn't the kind of reference a prospective employer is looking for. Use references you've worked for in the last five years. The exception here is if you've been with a company for ten years, you will need to go back that far to come up with a past supervisor.
My final comment on references is that you don't need to put "References Available Upon Request" or any other such statement on your resume. Employers know that if they require references (and most do), you will have to provide them. Otherwise, someone else will be hired. Use all the space on your resume to highlight your strengths instead.