The reference letter can be helpful in the employment process. A reference letter can provide potential employers with an idea of someone else's understanding of who you are and what qualifications you bring to the table. Even if a potential employer does not read the letter thoroughly, having a letter can make a difference in your job search.
The reference letter gives you an official endorsement from a former employer or someone who knows you well. A letter from a former employer can help you gain employment because it indicates to your new employer that you had a good relationship with your previous boss, that you made a contribution to his business that he remembers and that you left on amicable terms, rather than burning your bridges.
Summary of Qualifications
Another reason to obtain a reference letter from a former employer is that he can include a summary of your qualifications that reiterates what you have already stated in your resume. The former employer can and should highlight your most relevant work experience and the attributes that made you a valuable employee. It may be helpful to provide your previous employer with an updated resume, with specific job accomplishments and contributions, so that he'll have fresh information for the reference letter.
Another reason the reference letter can be important is that it may provide a window into your personality. The list of qualifications and accomplishments on your resume indicates that you are a good employee, but the potential employer may also want to know more about your personality and temperament. If your former employer knows enough about you to comment on your personality, it may suggest that there is more to you than your work history.
A reference letter from someone other than your employer can also help. A reference letter from someone respected in your field indicates your ability to network and influence people. If nothing it else, it can show that you are well-connected, especially if you are able to obtain a reference from an important or respected member of the community.