I have been a hiring manager for many recruitments in IT, and I am a huge fan of the cover letter.

Here are my general guidelines for what makes a good cover letter.

• Keep it short, but not too short. Your cover letter should be about 1 page or a little less. More than 1 page is a lot to ask the hiring committee to read. Less than half a page is not good, because people might think you are not motivated.
• Show knowledge of the job. The cover letter must absolutely demonstrate that you understand WHAT job you are applying for, and should highlight special things about you that would make you a great fit. You can say things like “I see that you are looking for X, and my experience with Y has really prepared me for that because… etc.”  Try to refer to the specific requirements in the job posting and connect them with your unique experience.
• Be less formal. The resume is typically a very formal instrument and can leave people wondering about some of your details. The cover letter gives you a chance to fill in details that might not be clear from a resume. For example, if you had a stretch of unemployment and you think people might find that odd, you can explain that in your cover letter. If you changed jobs a dozen times in one year, that’s probably worth a quick mention.
• Watch for tone. You can be a little less formal in the cover letter, which is why it is great, but don’t go too far. I have had applicants go on and on about irrelevant details and even practically threaten the hiring committee in the cover letter if we didn’t hire them. Don’t go there! Just keep your tone positive, enthusiastic and professional.
• Show attention to detail. Like the resume, you should have absolutely no typos or grammatical errors in your cover letter. Give it to someone else to proof-read. I don’t generally throw out applications for typographical errors, but I have been on hiring committees that did.

And that’s about it! Have fun writing your cover letter. When you’re done, read it and ask yourself: would I hire me? Even better, have someone else read it for you and answer that question.

And good luck in your job searching!