A cover letter accompanies your resume and describes why you are interested in and qualified for
a particular position.
It is usually the first thing an employer sees when he or she opens correspondence from you, and encourages that individual to read your resume by highlighting those aspects of your background and skills that most suit the employer’s needs.
Before you write a cover letter, research the employer and the position or field using company websites, Vault, news sources and MyCWS online resources. Each cover letter you write should be targeted to a specific employer and position; the cover letter should demonstrate your knowledge of the company and express an understanding of how your abilities align with the posted position. If you know a particular individual who has referred you to the company, always include this information.