The cover letter’s purpose is to create interest in your resume and personalize yourself with the recruiter. It is your introductory to your Resume. It should get the recruiter interested in you and want to read your Resume. The Cover Letter is the place you can use words such as “I, Me, You,” etc., and consists mostly of 3-5 paragraphs.
The first paragraph introduces you, states your objective, tells how you found the job, and is an introduction of the upcoming paragraphs. The next 1-3 paragraphs contain the meat of the cover letter, which means it is where you connect your skills, experience, and personal brand to the job you are applying for. It depends on your years of experience and level of the job that determines how many and how long these paragraphs should be. The average person only needs two paragraphs to sell themselves and drum up enough interest so that the employer is dying to read your resume.
The last paragraph is simply a restating of your intentions of landing that particular job, that you are a great match for this job, and that you will contact the employer within a week or so. Do not leave it up to them to call you back. It shows initiative and eagerness if you are taking the lead to contact them to set up an in-person interview.
After reading this you are probably going to go to Google and search Cover Letter samples, save yourself the time. I have a few samples just one-click away from Harvard, University at Buffalo, and either Stanford (Contemporary) or Stanford (Traditional). Stanford also has a presentation on Cover Letters.
Once you are all finished writing your new, amazing cover letter go over this checklist from Penn State University.