A cover letter, as used in the job_hunting context is a document that is supposed to provide an introduction to the resume or curriculum vitae, which are the basic document employed when marketing one's own services to a potential employer. In the traditional way of doing things (when job hunters used 'hard copy' applications), the 'cover letters' was typically attached on top of the curriculum vitae or resume, thereby typically serving a cover in the literal sense of the word, to the Curriculum vitae or resume; and it is probably from this fact that it probably got its name 'cover letter'.
Imagine a recruiter opening your cover letter to discover a title that addresses his top problem. How much more attractive will your packet seem? Go do two things right away: 1. Google "Johnson box for business letters" and learn about this terrific device, then 2. Brainstorm 7 headlines you could use for your cover letter format. With the fierce competition in this job market, having 113 applications on the street does you no good at all if each of them is mediocre. There are so many candidates, just one or two of them will create great packets and beat you every time.