Cover letters introduce you to prospective employers and motivate them to read your resume and learn more about your background and qualifications. These include letters of application, when you know of an opening and are writing to apply for it, and letters of inquiry, when you don't know if an opening exists but you want to explore employment possibilities with an organization.
Your cover letters, like your résumé, must be well written and contain no errors. The letters should add to the information that is presented in your résumé, not just repeat it. You want to catch the reader's attention with your good writing style, attention to detail, and statement of how your qualifications match the job requirements.
After you've used the resources available to develop your own letters, it's time to solicit input from others on your document. The staff, and peer advisors in ILR OCS, are available to review rough drafts of your cover letters.