In a company where I worked, we were in the market for a summer intern. One day, my boss dropped a resume on my desk. "Tell me what you think of this," he said. The truth was, there wasn't much to think. It was a list of jobs and colleges and a couple of awards I had never heard of. It looked OK, but I didn't know if I wanted to work with the person.

The next day, he handed me another application package. It had a resume, but it also had a letter with it that told us that the writer had a connection with our company. She knew something about us. She had had some unique travel experiences that made her a good fit for our operation -- in a way that we hadn't known we needed to advertise. We ended up inviting her in to interview for the intern position and then hiring her for a paid position that had opened unexpectedly.

What happened to the resume-only applicant? I don't remember.

A well-written cover letter gives a framework to understand the work experience and education listed on the resume. It's the whole person who does the job, and the whole person can't be captured in a resume. We've all known people with great resumes who couldn't do a day's work or couldn't get along with a friendly puppy. We've also known people whose work and people skills far surpassed what you could predict from the resume.

When you're applying for a job, you get a priceless chance to tell the employer who you are and what you can do for the company. Here are five reasons you don't want to omit the cover letter.

1. The cover letter sells the interview.

When you sit down to write your cover letter, you need to understand clearly what its job it. Of the application package, the resume tells whether you meet the basic qualifications for the job, and the cover letter makes the case for the interview. It's not going to sell you as an employee. That's too big for one page to do. What it does is to sell the interview. Once you get the interview -- and only if you get the interview -- you have an opportunity to make the case to hire you.

2. It makes a personal connection.

Write your covering letter so that your personality shines through. It gives a sense of what your unique strengths are. Sometimes people are afraid that if they reveal that they are, for example, a self-directed introvert, they will lose out with someone who is looking for a team-building extrovert. In fact, revealing that you have this kind of strength instead of that kind opens the door for a job that fits you, as well as closing the door to a job that doesn't. Hiding behind a dull and lifeless letter makes it impossible to find any job that fits. Use the cover letter to let the employer know who you are.

3. It fills in qualifications the resume can't cover.

We've all got strengths that our resume doesn't cover. Maybe the job you're applying for touches on a lifelong hobby. Maybe you've never had a job in childcare before, but you're the oldest of nine children. Maybe some secondary duties of a prior job make you uniquely qualified for this one. Maybe you've done some relevant volunteer work that didn't fit on a one-page resume. Whatever the case, your cover letter offers a chance to tell the employer about that extra qualification or to highlight something important part of you resume that you don't want the employer to miss.

4. It showcases your passion for the job.

If you take the time to do some research on the company, you can show that you're willing to make an extra effort for the sake of this job. You can refer to the company's mission statement, for example. You can also use strong and vibrant words that express your enthusiasm. An employer told me recently that for an advertised job, he got a stack of resumes a couple of inches high. "A lot of them are just looking for any job," he said. "That's OK, but we want someone who wants to work here." Every employer would agree. You can't express that enthusiasm without a cover letter.

5. It gives the reader a story, as opposed to a list of qualifications.

The secret to marketing copy is the story -- someone solving a problem. In the cover letter, the story is how you, the applicant, help the company overcome its obstacles or problems. In a one-page letter, it won't be in great detail, but just thinking through the question of problem-solution from the company's point of view, you can give your application a level of power that it can't get from just a resume.

The cover letter is an indispensable part of your application. Don't shortchange yourself by omitting it.