A cover letter though not a compulsion for application for any job is an extremely useful tool which can be used by prospective applicants to give the interviewer or the employer a brief idea or a conception of their interest and the expertise levelthe format of cover letter should be extremely formal and crisp and should contain a qualitative view of the resume attached.

Cover letter format spacing.
Why your job cover letter sucks and what you can do to fix it.
In your salutation you will set the tone for your letter which should be.
Examples of opening sentences to use when writing a cover letter plus tips for how to start and what to include in each part of a cover letter for a job.