In today's IT world, employers are inundated with responses to job postings, sometimes getting hundreds of resumes for a single job listing. Hiring managers and HR pros need to do what they can to whittle down the pile. For this reason, you've got to use every tool at your disposal to tell your story. The cover letter is a valuable tool in your arsenal that can help do just that.\n\n"By creating highly personalized and detailed cover letters, you will distinguish yourself from the crowd of other applicants who are sending the standard, boring cover letters that employers receive--and discard--every day," says Ford Myers, author of "Get The Job You Want, Even When No One's Hiring."\nIs it Always Necessary to Send a Cover Letter?"There are employers who religiously read every cover letter," says Doug Schade, principal consultant in the software technology search division at WinterWyman. While it may not be necessary, according to Schade, you definitely should if you have the opportunity. "My advice is to always include a short cover letter as you won't know the employer's propensities ahead of time and you may miss out on an opportunity to sell yourself. Every chance to tell your story is something you should take advantage of," says Doug Schade, principal consultant in the software technology search division at WinterWyman.Create a Custom Cover Letter"Customize your cover letter for each position," says John Reed, senior executive director at Robert Half Technology, a global IT staffing firm. Cover letters shouldn't be form letters. Each one should be unique to a specific company and the position you are applying for. Know Your Prospective EmployerFind out as much information as you can about your prospective employer, including the name of your hiring manager. You can use social media sites such as LinkedIn and Facebook. You could also comb through the company website.There are also sites out there that will help you research your prospective employer from afar offering insights and reviews from former employees as well as salary information. For more information on sites like this take a look at this article: 8 ways to Research Your Next Employer.4. Don't Repeat What's in Your Resume.Instead of simply repeating the details in your resume, focus on the job description and whatever else you can find out about the position and use the cover letter to show what value you bring to the table or what problem you can help them solve."Illustrate the specific skills you bring to the table and how they can help that employer. It really gives you an opportunity to create a customized commercial, if you will, that shows why you want to work for that specific company and how you can add value," says Reed.5. Make Sure Your Grammar and Punctuation Are SpotlessThis no-brainer has sunk more ships than you can imagine. "It's about attention to detail and this demonstrates the effectiveness of your written communication. You can have a spot-on profile and the perfect resume, but if you have grammatical and spelling errors or use slang--if it doesn't immediately disqualify you-- it puts you at a big disadvantage," says Reed. Poor grammar and punctuation are the quick way to the rejection pile so use spell check and have a friend or peer review it.The bottom line is to get more eyes on it. "They'll [peers] help you clean it up and shape it. They might catch potential grammar or spelling errors or offer insight like, 'I read this but I'm not sure what you mean' or 'when I read that, it didn't sound good. You may want to consider rewriting that sentence,' " says Reed.6. Set the Right ToneRemember that this is a formal business letter. It shouldn't be written as though you are writing a letter to a friend. You should strive to have a positive theme. Try reading it aloud a few times and if you're still unsure have a friend read it.7. Keep Your Cover Letter ConciseThe experts agree that the perfect cover letter should be short and succinct and consist of about three paragraphs. "A cover letter should be focused and no more than one page," says Dave Denaro, vice president at Keystone Associates an IT staffing firm. Here are Denaro's tips for building your cover letter. \nKeep it to three paragraphs:\n\n Paragraph 1: State why you are responding, particularly if it was an internal referral recommendation.\n Paragraph 2: Explain the match between what they say they need delivered in the posting versus the same or similar accomplishments that you've been able to produce.\n Paragraph 3: A couple of sentences that suggest that you would love to come in and discuss the position at their earliest convenience--over the next couple of weeks in particular, if possible.\n\nThat said, Myer does offer one exception for what he calls the dream match. This is a job listing that you feel passionate about and, more importantly, your skills match is perfect. In this instance, he says, write an opening paragraph and create two columns beneath. In the left column, place the skills that are in the job listing or the ones the employer are looking for. In the right column, against each skill on the left you'll briefly outline how your experience or skill meets or exceeds their request, for example.Myers offers an example of a dream match cover letter.8. Make Your Cover Letter PersonalExperts agree that it's wise to try to figure out who the hiring manager is and address your cover letter to that person. LinkedIn or Facebook will likely yield the answer but you could also simply call and ask. "Find out who the hiring manager is and address it to that person. It's going to make the person who receives it comfortable because you've done your homework," says Reed.If you've tried to find out who the hiring manager is, but haven't been able to do so you can avoid the obligatory 'To Whom It May Concern' line. Experts say to not address it to anyone and simply begin with your opening paragraphs.9. Briefly Outline Your AccomplishmentsThis is an opportunity to demonstrate to the potential employer how your accomplishments are going to help the employer achieve their business goals. Use the job description and whatever information you can glean about the role and then come up with an achievement or accomplishment in your work experience that is similar.When you take the time to read through the description and come up with a unique cover letter Reed says, "You are demonstrating to the employer that 'I've read your job description; I think I understand what you are looking for. I can do that job and do it very well and here's why.' ""In constructing a cover letter, look at the job description or job posting to decide what the hiring manager is looking for you to do, for you to deliver; then in the cover letter make sure that you mention that you have handled that issue, that problem or that challenge before successfully by adding a one-line bullet about the results that you produced," says Denaro.Choosing your accomplishments to add to the cover letter wisely will help demonstrate that you've dealt with the same types of problems they are currently dealing with and, more importantly, how you can help. "It shows that you know the company well, that you've done your homework and that you're familiar with the challenges and opportunities in their industry --or better yet, at their organization in particular," says Myers.10. Create a Consistent PackageYou should try to create a uniform appearance between your cover letter and your resume. You don't want them to look as though they were written by different people or at different times. The font, colors and appearance should all be the same. "You want it to appear like a consistent, unified and integrated package. It should mirror the resume in style and font," says Reed.11. Convey Your Passion and ExcitementThis can be more difficult than it sounds because showing excitement without sounding corny is hard to pull off. The experts do offer some advice, though.Reed offers this approach to the conundrum. "Identify a next step, for example, 'I'll follow-up next week to discuss meeting you in person.' That conveys that you are excited about the position and about meeting in person," says Reed."You could coldly list duties or responsibilities you had in the past, not calibrating the reader as to how well you did it or how much satisfaction you got out of doing it. It is better that you tell what you accomplished, the result you produced for your firm and state that is was tremendously satisfying to have delivered in this manner," says Denaro.12. Use the Most Relevant Keywords"Both humans and resume management systems are attracted by the use of keywords," says Denaro.Use keywords in your cover letter that are relevant to the position you are applying for. "There are companies where your submission will go through a software package and it will scan to see if there are the keywords that match the job description. Maybe the employer wants someone who is a database administrator, who knows SQL server and has worked with stored procedures. The cover letter offers an opportunity to highlight those skills by saying something such as, "I see you're looking for a database administrator, I'm a database administrator and I have SQL server experience and I've worked with stored procedures," says Reed.It's important to be diligent here. Ensure that the keywords you're using align with the job listing. You wouldn't want to be excluded because you used the different or the wrong terminology. The takeaway here is you want to make sure in your cover letter that you mirror and match the term the employers use.Don't overdo it though because both human and software will know and likely ding you for keyword stuffing. "It's important to use keywords to a point," says Reed. You don't want to force anything in there so try to keep it natural sounding.13. Use a Consistent FormatYou want to make sure your cover letter and resume are locked down in PDF format to prevent any unintended changes. This is your data after all and often it's the only impression of you a prospective employer will get prior to a phone or in-person interview. Rich Hein is a senior writer for CIO.com. He covers IT careers. Follow everything from CIO.com on Twitter @CIOonline, on Facebook, and on Google +.