clipped from: www.cheezhead.com   

why cover letters are essential

A team from TheLadders selected the most important criteria that should be included in the cover letter:

Get Their Attention — A cover letter must grab a reader’s attention in a split-second with a succinct message that convinces them to read further.
Less is More — A good cover letter should clearly convey the “who,” “what,” “when,” “where” and “why” in the first paragraph and be no longer than three or four total paragraphs.

Prove Relevance — Job seekers should mine the job posting and company Web site for the specific words and clues to what the employer is looking for in a candidate and use those words in the cover letter.

Turn Negatives Into Positives — The cover letter is where you can explain unique situations before they are red flagged on your resume.

Paste and Attach — If you are applying via e-mail, cut and paste the cover letter to make it your e-mail message and attach it.