An application letter—the letter you write to apply for a job—will probably be the most important kind of letter you will ever write. Very likely, it is a letter that you will write several times, as most people change employers several times during their business careers. Your first job, as well as each of those that follow, is almost certain to involve some writing—and most employers look upon an application letter as an excellent indicator (标志)of an applicant’s (应聘者) writing and other communication skills.
The purpose of your application letter, which should go together with your resume, is to get you an in-person interview with the employer if the letter is a good one, it most likely will achieve its objective.
The general plan of an application letter closely matches that of a sales letter. For an application letter, the "product" you are selling consists of your knowledge, your skills, your personality—everything about you that will enable you to perform the job to the satisfaction of employer. As a result, you must understand the employer’s needs, know the specific requirements of the job you are seeking, and know what you have to "sell".
The waiter of this passage compares an application letter to ______.